[PATCH v2 00/13] PCI: aardvark controller fixes

[PATCH v2 00/13] PCI: aardvark controller fixes

[Marek Behún]

Hi Lorenzo,

as requested I am sending v2 of this series.

Changes since v1:
- updated commit message in patch 6 as suggested by Mark
- updated patch 6 to also drop the early return
- changed the LTSSM definitions to enum in patch 12
- dropped the Fixes tags for those patches where it was inappropriate

Marek Behún (2):
  PCI: aardvark: Don't spam about PIO Response Status
  PCI: aardvark: Deduplicate code in advk_pcie_rd_conf()

Pali Rohár (11):
  PCI: Add PCI_EXP_DEVCTL_PAYLOAD_* macros
  PCI: aardvark: Fix PCIe Max Payload Size setting
  PCI: aardvark: Fix preserving PCI_EXP_RTCTL_CRSSVE flag on emulated
    bridge
  PCI: aardvark: Fix configuring Reference clock
  PCI: aardvark: Do not clear status bits of masked interrupts
  PCI: aardvark: Do not unmask unused interrupts
  PCI: aardvark: Implement re-issuing config requests on CRS response
  PCI: aardvark: Simplify initialization of rootcap on virtual bridge
  PCI: aardvark: Fix link training
  PCI: aardvark: Fix checking for link up via LTSSM state
  PCI: aardvark: Fix reporting Data Link Layer Link Active

 drivers/pci/controller/pci-aardvark.c | 372 +++++++++++++++-----------
 include/uapi/linux/pci_regs.h         |   6 +
 2 files changed, 217 insertions(+), 161 deletions(-)

-- 
2.32.0

[PATCH v2 01/13] PCI: Add PCI_EXP_DEVCTL_PAYLOAD_* macros

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

Define a macro PCI_EXP_DEVCTL_PAYLOAD_* for every possible Max Payload
Size in linux/pci_regs.h, in the same style as PCI_EXP_DEVCTL_READRQ_*.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Marek Behún <kabel@kernel.org>
---
 include/uapi/linux/pci_regs.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index e709ae8235e7..ff6ccbc6efe9 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -504,6 +504,12 @@
 #define  PCI_EXP_DEVCTL_URRE	0x0008	/* Unsupported Request Reporting En. */
 #define  PCI_EXP_DEVCTL_RELAX_EN 0x0010 /* Enable relaxed ordering */
 #define  PCI_EXP_DEVCTL_PAYLOAD	0x00e0	/* Max_Payload_Size */
+#define  PCI_EXP_DEVCTL_PAYLOAD_128B 0x0000 /* 128 Bytes */
+#define  PCI_EXP_DEVCTL_PAYLOAD_256B 0x0020 /* 256 Bytes */
+#define  PCI_EXP_DEVCTL_PAYLOAD_512B 0x0040 /* 512 Bytes */
+#define  PCI_EXP_DEVCTL_PAYLOAD_1024B 0x0060 /* 1024 Bytes */
+#define  PCI_EXP_DEVCTL_PAYLOAD_2048B 0x0080 /* 2048 Bytes */
+#define  PCI_EXP_DEVCTL_PAYLOAD_4096B 0x00a0 /* 4096 Bytes */
 #define  PCI_EXP_DEVCTL_EXT_TAG	0x0100	/* Extended Tag Field Enable */
 #define  PCI_EXP_DEVCTL_PHANTOM	0x0200	/* Phantom Functions Enable */
 #define  PCI_EXP_DEVCTL_AUX_PME	0x0400	/* Auxiliary Power PM Enable */
-- 
2.32.0

[PATCH v2 02/13] PCI: aardvark: Fix PCIe Max Payload Size setting

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

Change PCIe Max Payload Size setting in PCIe Device Control register to 512
bytes to align with PCIe Link Initialization sequence as defined in Marvell
Armada 3700 Functional Specification. According to the specification,
maximal Max Payload Size supported by this device is 512 bytes.

Without this kernel prints suspicious line:

    pci 0000:01:00.0: Upstream bridge's Max Payload Size set to 256 (was 16384, max 512)

With this change it changes to:

    pci 0000:01:00.0: Upstream bridge's Max Payload Size set to 256 (was 512, max 512)

Fixes: 8c39d710363c ("PCI: aardvark: Add Aardvark PCI host controller driver")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: stable@vger.kernel.org
---
 drivers/pci/controller/pci-aardvark.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 596ebcfcc82d..884510630bae 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -488,8 +488,9 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
 	reg = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + PCI_EXP_DEVCTL);
 	reg &= ~PCI_EXP_DEVCTL_RELAX_EN;
 	reg &= ~PCI_EXP_DEVCTL_NOSNOOP_EN;
+	reg &= ~PCI_EXP_DEVCTL_PAYLOAD;
 	reg &= ~PCI_EXP_DEVCTL_READRQ;
-	reg |= PCI_EXP_DEVCTL_PAYLOAD; /* Set max payload size */
+	reg |= PCI_EXP_DEVCTL_PAYLOAD_512B;
 	reg |= PCI_EXP_DEVCTL_READRQ_512B;
 	advk_writel(pcie, reg, PCIE_CORE_PCIEXP_CAP + PCI_EXP_DEVCTL);
 
-- 
2.32.0

[PATCH v2 03/13] PCI: aardvark: Don't spam about PIO Response Status

[Marek Behún]

Use dev_dbg() instead of dev_err() in advk_pcie_check_pio_status().

For example CRS is not an error status, it just says that the request
should be retried.

Fixes: 8c39d710363c1 ("PCI: aardvark: Add Aardvark PCI host controller driver")
Signed-off-by: Marek Behún <kabel@kernel.org>
---
 drivers/pci/controller/pci-aardvark.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 884510630bae..a7903c531aa3 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -683,7 +683,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3
 	else
 		str_posted = "Posted";
 
-	dev_err(dev, "%s PIO Response Status: %s, %#x @ %#x\n",
+	dev_dbg(dev, "%s PIO Response Status: %s, %#x @ %#x\n",
 		str_posted, strcomp_status, reg, advk_readl(pcie, PIO_ADDR_LS));
 
 	return -EFAULT;
-- 
2.32.0

[PATCH v2 04/13] PCI: aardvark: Fix preserving PCI_EXP_RTCTL_CRSSVE flag on emulated bridge

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

Commit 43f5c77bcbd2 ("PCI: aardvark: Fix reporting CRS value") started
using CRSSVE flag for handling CRS responses.

PCI_EXP_RTCTL_CRSSVE flag is stored only in emulated config space buffer
and there is handler for PCI_EXP_RTCTL register. So every read operation
from config space automatically clears CRSSVE flag as it is not defined in
PCI_EXP_RTCTL read handler.

Fix this by reading current CRSSVE bit flag from emulated space buffer and
appending it to PCI_EXP_RTCTL read response.

Fixes: 43f5c77bcbd2 ("PCI: aardvark: Fix reporting CRS value")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
---
 drivers/pci/controller/pci-aardvark.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index a7903c531aa3..bb57ca6aed35 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -724,6 +724,7 @@ advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 	case PCI_EXP_RTCTL: {
 		u32 val = advk_readl(pcie, PCIE_ISR0_MASK_REG);
 		*value = (val & PCIE_MSG_PM_PME_MASK) ? 0 : PCI_EXP_RTCTL_PMEIE;
+		*value |= le16_to_cpu(bridge->pcie_conf.rootctl) & PCI_EXP_RTCTL_CRSSVE;
 		*value |= PCI_EXP_RTCAP_CRSVIS << 16;
 		return PCI_BRIDGE_EMUL_HANDLED;
 	}
-- 
2.32.0

[PATCH v2 05/13] PCI: aardvark: Fix configuring Reference clock

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

Commit 366697018c9a ("PCI: aardvark: Add PHY support") introduced
configuration of PCIe Reference clock via PCIE_CORE_REF_CLK_REG register,
but did it incorrectly.

PCIe Reference clock differential pair is routed from system board to
endpoint card, so on CPU side it has output direction. Therefore it is
required to enable transmitting and disable receiving.

Default configuration according to Armada 3700 Functional Specifications is
enabled receiver part and disabled transmitter.

We need this change because otherwise PCIe Reference clock is configured to
some undefined state when differential pair is used for both transmitting
and receiving.

Fix this by disabling receiver part.

Fixes: 366697018c9a ("PCI: aardvark: Add PHY support")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: stable@vger.kernel.org
---
 drivers/pci/controller/pci-aardvark.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index bb57ca6aed35..d5d6f92e5143 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -99,6 +99,7 @@
 #define     PCIE_CORE_CTRL2_MSI_ENABLE		BIT(10)
 #define PCIE_CORE_REF_CLK_REG			(CONTROL_BASE_ADDR + 0x14)
 #define     PCIE_CORE_REF_CLK_TX_ENABLE		BIT(1)
+#define     PCIE_CORE_REF_CLK_RX_ENABLE		BIT(2)
 #define PCIE_MSG_LOG_REG			(CONTROL_BASE_ADDR + 0x30)
 #define PCIE_ISR0_REG				(CONTROL_BASE_ADDR + 0x40)
 #define PCIE_MSG_PM_PME_MASK			BIT(7)
@@ -451,9 +452,15 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
 	u32 reg;
 	int i;
 
-	/* Enable TX */
+	/*
+	 * Configure PCIe Reference clock. Direction is from the PCIe
+	 * controller to the endpoint card, so enable transmitting of
+	 * Reference clock differential signal off-chip and disable
+	 * receiving off-chip differential signal.
+	 */
 	reg = advk_readl(pcie, PCIE_CORE_REF_CLK_REG);
 	reg |= PCIE_CORE_REF_CLK_TX_ENABLE;
+	reg &= ~PCIE_CORE_REF_CLK_RX_ENABLE;
 	advk_writel(pcie, reg, PCIE_CORE_REF_CLK_REG);
 
 	/* Set to Direct mode */
-- 
2.32.0

[PATCH v2 06/13] PCI: aardvark: Do not clear status bits of masked interrupts

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

The PCIE_ISR1_REG says which interrupts are currently set / active,
including those which are masked.

The driver currently reads this register and looks if some unmasked
interrupts are active, and if not, it clears status bits of _all_
interrupts, including the masked ones.

This is incorrect, since, for example, some drivers may poll these bits.

Remove this clearing, and also remove this early return statement
completely, since it does not change functionality in any way.

Fixes: 8c39d710363c ("PCI: aardvark: Add Aardvark PCI host controller driver")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: stable@vger.kernel.org
---
 drivers/pci/controller/pci-aardvark.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index d5d6f92e5143..f7eebf453e83 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -1295,12 +1295,6 @@ static void advk_pcie_handle_int(struct advk_pcie *pcie)
 	isr1_mask = advk_readl(pcie, PCIE_ISR1_MASK_REG);
 	isr1_status = isr1_val & ((~isr1_mask) & PCIE_ISR1_ALL_MASK);
 
-	if (!isr0_status && !isr1_status) {
-		advk_writel(pcie, isr0_val, PCIE_ISR0_REG);
-		advk_writel(pcie, isr1_val, PCIE_ISR1_REG);
-		return;
-	}
-
 	/* Process MSI interrupts */
 	if (isr0_status & PCIE_ISR0_MSI_INT_PENDING)
 		advk_pcie_handle_msi(pcie);
-- 
2.32.0

[PATCH v2 07/13] PCI: aardvark: Do not unmask unused interrupts

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

There are lot of undocumented interrupt bits. Fix all *_ALL_MASK macros to
define all interrupt bits, so that driver can properly mask all interrupts,
including those which are undocumented.

Fixes: 8c39d710363c ("PCI: aardvark: Add Aardvark PCI host controller driver")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: stable@vger.kernel.org
---
 drivers/pci/controller/pci-aardvark.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index f7eebf453e83..3448a8c446d4 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -107,13 +107,13 @@
 #define     PCIE_ISR0_MSI_INT_PENDING		BIT(24)
 #define     PCIE_ISR0_INTX_ASSERT(val)		BIT(16 + (val))
 #define     PCIE_ISR0_INTX_DEASSERT(val)	BIT(20 + (val))
-#define	    PCIE_ISR0_ALL_MASK			GENMASK(26, 0)
+#define     PCIE_ISR0_ALL_MASK			GENMASK(31, 0)
 #define PCIE_ISR1_REG				(CONTROL_BASE_ADDR + 0x48)
 #define PCIE_ISR1_MASK_REG			(CONTROL_BASE_ADDR + 0x4C)
 #define     PCIE_ISR1_POWER_STATE_CHANGE	BIT(4)
 #define     PCIE_ISR1_FLUSH			BIT(5)
 #define     PCIE_ISR1_INTX_ASSERT(val)		BIT(8 + (val))
-#define     PCIE_ISR1_ALL_MASK			GENMASK(11, 4)
+#define     PCIE_ISR1_ALL_MASK			GENMASK(31, 0)
 #define PCIE_MSI_ADDR_LOW_REG			(CONTROL_BASE_ADDR + 0x50)
 #define PCIE_MSI_ADDR_HIGH_REG			(CONTROL_BASE_ADDR + 0x54)
 #define PCIE_MSI_STATUS_REG			(CONTROL_BASE_ADDR + 0x58)
@@ -199,7 +199,7 @@
 #define     PCIE_IRQ_MSI_INT2_DET		BIT(21)
 #define     PCIE_IRQ_RC_DBELL_DET		BIT(22)
 #define     PCIE_IRQ_EP_STATUS			BIT(23)
-#define     PCIE_IRQ_ALL_MASK			0xfff0fb
+#define     PCIE_IRQ_ALL_MASK			GENMASK(31, 0)
 #define     PCIE_IRQ_ENABLE_INTS_MASK		PCIE_IRQ_CORE_INT
 
 /* Transaction types */
-- 
2.32.0

Re: [PATCH v2 07/13] PCI: aardvark: Do not unmask unused interrupts

[Lorenzo Pieralisi]

[CC Sasha for stable kernel rules]

On Tue, Oct 05, 2021 at 08:09:46PM +0200, Marek Behún wrote:
> From: Pali Rohár <pali@kernel.org>
> 
> There are lot of undocumented interrupt bits. Fix all *_ALL_MASK macros to
> define all interrupt bits, so that driver can properly mask all interrupts,
> including those which are undocumented.
> 
> Fixes: 8c39d710363c ("PCI: aardvark: Add Aardvark PCI host controller driver")
> Signed-off-by: Pali Rohár <pali@kernel.org>
> Reviewed-by: Marek Behún <kabel@kernel.org>
> Signed-off-by: Marek Behún <kabel@kernel.org>
> Cc: stable@vger.kernel.org

I don't think this is a fix and I don't think it should be sent
to stable kernels in _preparation_ for other fixes to come (that
may never land in mainline).

If, for future fixes a depedency is detected they can be added
in the relevant commit log.

That's my understanding, Sasha can clarify if needed.

Patch itself is fine.

Thanks,
Lorenzo

> ---
>  drivers/pci/controller/pci-aardvark.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index f7eebf453e83..3448a8c446d4 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -107,13 +107,13 @@
>  #define     PCIE_ISR0_MSI_INT_PENDING		BIT(24)
>  #define     PCIE_ISR0_INTX_ASSERT(val)		BIT(16 + (val))
>  #define     PCIE_ISR0_INTX_DEASSERT(val)	BIT(20 + (val))
> -#define	    PCIE_ISR0_ALL_MASK			GENMASK(26, 0)
> +#define     PCIE_ISR0_ALL_MASK			GENMASK(31, 0)
>  #define PCIE_ISR1_REG				(CONTROL_BASE_ADDR + 0x48)
>  #define PCIE_ISR1_MASK_REG			(CONTROL_BASE_ADDR + 0x4C)
>  #define     PCIE_ISR1_POWER_STATE_CHANGE	BIT(4)
>  #define     PCIE_ISR1_FLUSH			BIT(5)
>  #define     PCIE_ISR1_INTX_ASSERT(val)		BIT(8 + (val))
> -#define     PCIE_ISR1_ALL_MASK			GENMASK(11, 4)
> +#define     PCIE_ISR1_ALL_MASK			GENMASK(31, 0)
>  #define PCIE_MSI_ADDR_LOW_REG			(CONTROL_BASE_ADDR + 0x50)
>  #define PCIE_MSI_ADDR_HIGH_REG			(CONTROL_BASE_ADDR + 0x54)
>  #define PCIE_MSI_STATUS_REG			(CONTROL_BASE_ADDR + 0x58)
> @@ -199,7 +199,7 @@
>  #define     PCIE_IRQ_MSI_INT2_DET		BIT(21)
>  #define     PCIE_IRQ_RC_DBELL_DET		BIT(22)
>  #define     PCIE_IRQ_EP_STATUS			BIT(23)
> -#define     PCIE_IRQ_ALL_MASK			0xfff0fb
> +#define     PCIE_IRQ_ALL_MASK			GENMASK(31, 0)
>  #define     PCIE_IRQ_ENABLE_INTS_MASK		PCIE_IRQ_CORE_INT
>  
>  /* Transaction types */
> -- 
> 2.32.0
> 

Re: [PATCH v2 07/13] PCI: aardvark: Do not unmask unused interrupts

[Marek Behún]

On Wed, 6 Oct 2021 10:13:38 +0100
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote:

> [CC Sasha for stable kernel rules]
> 
> On Tue, Oct 05, 2021 at 08:09:46PM +0200, Marek Behún wrote:
> > From: Pali Rohár <pali@kernel.org>
> > 
> > There are lot of undocumented interrupt bits. Fix all *_ALL_MASK macros to
> > define all interrupt bits, so that driver can properly mask all interrupts,
> > including those which are undocumented.
> > 
> > Fixes: 8c39d710363c ("PCI: aardvark: Add Aardvark PCI host controller driver")
> > Signed-off-by: Pali Rohár <pali@kernel.org>
> > Reviewed-by: Marek Behún <kabel@kernel.org>
> > Signed-off-by: Marek Behún <kabel@kernel.org>
> > Cc: stable@vger.kernel.org  
> 
> I don't think this is a fix and I don't think it should be sent
> to stable kernels in _preparation_ for other fixes to come (that
> may never land in mainline).

This patch is a fix because it fixes masking interrupts, which may
prevent spurious interrupts - we don't want interrupts which kernel
didn't request for.

I agree that the commit message should probably mention this, though...
:(

Marek

Re: [PATCH v2 07/13] PCI: aardvark: Do not unmask unused interrupts

[Lorenzo Pieralisi]

On Wed, Oct 06, 2021 at 12:28:23PM +0200, Marek Behún wrote:
> On Wed, 6 Oct 2021 10:13:38 +0100
> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote:
> 
> > [CC Sasha for stable kernel rules]
> > 
> > On Tue, Oct 05, 2021 at 08:09:46PM +0200, Marek Behún wrote:
> > > From: Pali Rohár <pali@kernel.org>
> > > 
> > > There are lot of undocumented interrupt bits. Fix all *_ALL_MASK macros to
> > > define all interrupt bits, so that driver can properly mask all interrupts,
> > > including those which are undocumented.
> > > 
> > > Fixes: 8c39d710363c ("PCI: aardvark: Add Aardvark PCI host controller driver")
> > > Signed-off-by: Pali Rohár <pali@kernel.org>
> > > Reviewed-by: Marek Behún <kabel@kernel.org>
> > > Signed-off-by: Marek Behún <kabel@kernel.org>
> > > Cc: stable@vger.kernel.org  
> > 
> > I don't think this is a fix and I don't think it should be sent
> > to stable kernels in _preparation_ for other fixes to come (that
> > may never land in mainline).
> 
> This patch is a fix because it fixes masking interrupts, which may
> prevent spurious interrupts - we don't want interrupts which kernel
> didn't request for.
> 
> I agree that the commit message should probably mention this, though...
> :(

Now it does ;-), will notify you when I push the series out so that
you can have a look to check.

Thanks,
Lorenzo

> 
> Marek

[PATCH v2 08/13] PCI: aardvark: Deduplicate code in advk_pcie_rd_conf()

[Marek Behún]

Avoid code repetition in advk_pcie_rd_conf() by handling errors with
goto jump, as is customary in kernel.

Fixes: 43f5c77bcbd2 ("PCI: aardvark: Fix reporting CRS value")
Signed-off-by: Marek Behún <kabel@kernel.org>
---
 drivers/pci/controller/pci-aardvark.c | 48 +++++++++++----------------
 1 file changed, 20 insertions(+), 28 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 3448a8c446d4..cd5be284789e 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -920,18 +920,8 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
 		    (le16_to_cpu(pcie->bridge.pcie_conf.rootctl) &
 		     PCI_EXP_RTCTL_CRSSVE);
 
-	if (advk_pcie_pio_is_running(pcie)) {
-		/*
-		 * If it is possible return Completion Retry Status so caller
-		 * tries to issue the request again instead of failing.
-		 */
-		if (allow_crs) {
-			*val = CFG_RD_CRS_VAL;
-			return PCIBIOS_SUCCESSFUL;
-		}
-		*val = 0xffffffff;
-		return PCIBIOS_SET_FAILED;
-	}
+	if (advk_pcie_pio_is_running(pcie))
+		goto try_crs;
 
 	/* Program the control register */
 	reg = advk_readl(pcie, PIO_CTRL);
@@ -955,25 +945,13 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
 	advk_writel(pcie, 1, PIO_START);
 
 	ret = advk_pcie_wait_pio(pcie);
-	if (ret < 0) {
-		/*
-		 * If it is possible return Completion Retry Status so caller
-		 * tries to issue the request again instead of failing.
-		 */
-		if (allow_crs) {
-			*val = CFG_RD_CRS_VAL;
-			return PCIBIOS_SUCCESSFUL;
-		}
-		*val = 0xffffffff;
-		return PCIBIOS_SET_FAILED;
-	}
+	if (ret < 0)
+		goto try_crs;
 
 	/* Check PIO status and get the read result */
 	ret = advk_pcie_check_pio_status(pcie, allow_crs, val);
-	if (ret < 0) {
-		*val = 0xffffffff;
-		return PCIBIOS_SET_FAILED;
-	}
+	if (ret < 0)
+		goto fail;
 
 	if (size == 1)
 		*val = (*val >> (8 * (where & 3))) & 0xff;
@@ -981,6 +959,20 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
 		*val = (*val >> (8 * (where & 3))) & 0xffff;
 
 	return PCIBIOS_SUCCESSFUL;
+
+try_crs:
+	/*
+	 * If it is possible, return Completion Retry Status so that caller
+	 * tries to issue the request again instead of failing.
+	 */
+	if (allow_crs) {
+		*val = CFG_RD_CRS_VAL;
+		return PCIBIOS_SUCCESSFUL;
+	}
+
+fail:
+	*val = 0xffffffff;
+	return PCIBIOS_SET_FAILED;
 }
 
 static int advk_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
-- 
2.32.0

[PATCH v2 09/13] PCI: aardvark: Implement re-issuing config requests on CRS response

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

Commit 43f5c77bcbd2 ("PCI: aardvark: Fix reporting CRS value") fixed
handling of CRS response and when CRSSVE flag was not enabled it marked CRS
response as failed transaction (due to simplicity).

But pci-aardvark.c driver is already waiting up to the PIO_RETRY_CNT count
for PIO config response and so we can with a small change implement
re-issuing of config requests as described in PCIe base specification.

This change implements re-issuing of config requests when response is CRS.
Set upper bound of wait cycles to around PIO_RETRY_CNT, afterwards the
transaction is marked as failed and an all-ones value is returned as
before.

We do this by returning appropriate error codes from function
advk_pcie_check_pio_status(). On CRS we return -EAGAIN and caller then
reissues transaction.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
---
 drivers/pci/controller/pci-aardvark.c | 67 +++++++++++++++++----------
 1 file changed, 43 insertions(+), 24 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index cd5be284789e..efe8b5f7bf8c 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -603,6 +603,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3
 	u32 reg;
 	unsigned int status;
 	char *strcomp_status, *str_posted;
+	int ret;
 
 	reg = advk_readl(pcie, PIO_STAT);
 	status = (reg & PIO_COMPLETION_STATUS_MASK) >>
@@ -627,6 +628,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3
 	case PIO_COMPLETION_STATUS_OK:
 		if (reg & PIO_ERR_STATUS) {
 			strcomp_status = "COMP_ERR";
+			ret = -EFAULT;
 			break;
 		}
 		/* Get the read result */
@@ -634,9 +636,11 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3
 			*val = advk_readl(pcie, PIO_RD_DATA);
 		/* No error */
 		strcomp_status = NULL;
+		ret = 0;
 		break;
 	case PIO_COMPLETION_STATUS_UR:
 		strcomp_status = "UR";
+		ret = -EOPNOTSUPP;
 		break;
 	case PIO_COMPLETION_STATUS_CRS:
 		if (allow_crs && val) {
@@ -654,6 +658,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3
 			 */
 			*val = CFG_RD_CRS_VAL;
 			strcomp_status = NULL;
+			ret = 0;
 			break;
 		}
 		/* PCIe r4.0, sec 2.3.2, says:
@@ -669,21 +674,24 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3
 		 * Request and taking appropriate action, e.g., complete the
 		 * Request to the host as a failed transaction.
 		 *
-		 * To simplify implementation do not re-issue the Configuration
-		 * Request and complete the Request as a failed transaction.
+		 * So return -EAGAIN and caller (pci-aardvark.c driver) will
+		 * re-issue request again up to the PIO_RETRY_CNT retries.
 		 */
 		strcomp_status = "CRS";
+		ret = -EAGAIN;
 		break;
 	case PIO_COMPLETION_STATUS_CA:
 		strcomp_status = "CA";
+		ret = -ECANCELED;
 		break;
 	default:
 		strcomp_status = "Unknown";
+		ret = -EINVAL;
 		break;
 	}
 
 	if (!strcomp_status)
-		return 0;
+		return ret;
 
 	if (reg & PIO_NON_POSTED_REQ)
 		str_posted = "Non-posted";
@@ -693,7 +701,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3
 	dev_dbg(dev, "%s PIO Response Status: %s, %#x @ %#x\n",
 		str_posted, strcomp_status, reg, advk_readl(pcie, PIO_ADDR_LS));
 
-	return -EFAULT;
+	return ret;
 }
 
 static int advk_pcie_wait_pio(struct advk_pcie *pcie)
@@ -701,13 +709,13 @@ static int advk_pcie_wait_pio(struct advk_pcie *pcie)
 	struct device *dev = &pcie->pdev->dev;
 	int i;
 
-	for (i = 0; i < PIO_RETRY_CNT; i++) {
+	for (i = 1; i <= PIO_RETRY_CNT; i++) {
 		u32 start, isr;
 
 		start = advk_readl(pcie, PIO_START);
 		isr = advk_readl(pcie, PIO_ISR);
 		if (!start && isr)
-			return 0;
+			return i;
 		udelay(PIO_RETRY_DELAY);
 	}
 
@@ -898,6 +906,7 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
 			     int where, int size, u32 *val)
 {
 	struct advk_pcie *pcie = bus->sysdata;
+	int retry_count;
 	bool allow_crs;
 	u32 reg;
 	int ret;
@@ -940,16 +949,22 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
 	/* Program the data strobe */
 	advk_writel(pcie, 0xf, PIO_WR_DATA_STRB);
 
-	/* Clear PIO DONE ISR and start the transfer */
-	advk_writel(pcie, 1, PIO_ISR);
-	advk_writel(pcie, 1, PIO_START);
+	retry_count = 0;
+	do {
+		/* Clear PIO DONE ISR and start the transfer */
+		advk_writel(pcie, 1, PIO_ISR);
+		advk_writel(pcie, 1, PIO_START);
 
-	ret = advk_pcie_wait_pio(pcie);
-	if (ret < 0)
-		goto try_crs;
+		ret = advk_pcie_wait_pio(pcie);
+		if (ret < 0)
+			goto try_crs;
+
+		retry_count += ret;
+
+		/* Check PIO status and get the read result */
+		ret = advk_pcie_check_pio_status(pcie, allow_crs, val);
+	} while (ret == -EAGAIN && retry_count < PIO_RETRY_CNT);
 
-	/* Check PIO status and get the read result */
-	ret = advk_pcie_check_pio_status(pcie, allow_crs, val);
 	if (ret < 0)
 		goto fail;
 
@@ -981,6 +996,7 @@ static int advk_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
 	struct advk_pcie *pcie = bus->sysdata;
 	u32 reg;
 	u32 data_strobe = 0x0;
+	int retry_count;
 	int offset;
 	int ret;
 
@@ -1022,19 +1038,22 @@ static int advk_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
 	/* Program the data strobe */
 	advk_writel(pcie, data_strobe, PIO_WR_DATA_STRB);
 
-	/* Clear PIO DONE ISR and start the transfer */
-	advk_writel(pcie, 1, PIO_ISR);
-	advk_writel(pcie, 1, PIO_START);
+	retry_count = 0;
+	do {
+		/* Clear PIO DONE ISR and start the transfer */
+		advk_writel(pcie, 1, PIO_ISR);
+		advk_writel(pcie, 1, PIO_START);
 
-	ret = advk_pcie_wait_pio(pcie);
-	if (ret < 0)
-		return PCIBIOS_SET_FAILED;
+		ret = advk_pcie_wait_pio(pcie);
+		if (ret < 0)
+			return PCIBIOS_SET_FAILED;
 
-	ret = advk_pcie_check_pio_status(pcie, false, NULL);
-	if (ret < 0)
-		return PCIBIOS_SET_FAILED;
+		retry_count += ret;
 
-	return PCIBIOS_SUCCESSFUL;
+		ret = advk_pcie_check_pio_status(pcie, false, NULL);
+	} while (ret == -EAGAIN && retry_count < PIO_RETRY_CNT);
+
+	return ret < 0 ? PCIBIOS_SET_FAILED : PCIBIOS_SUCCESSFUL;
 }
 
 static struct pci_ops advk_pcie_ops = {
-- 
2.32.0

[PATCH v2 10/13] PCI: aardvark: Simplify initialization of rootcap on virtual bridge

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

PCIe config space can be initialized also before pci_bridge_emul_init()
call, so move rootcap initialization after PCI config space initialization.

This simplifies the function a little since it removes one if (ret < 0)
check.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
---
 drivers/pci/controller/pci-aardvark.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index efe8b5f7bf8c..9c509d5a9afa 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -822,7 +822,6 @@ static struct pci_bridge_emul_ops advk_pci_bridge_emul_ops = {
 static int advk_sw_pci_bridge_init(struct advk_pcie *pcie)
 {
 	struct pci_bridge_emul *bridge = &pcie->bridge;
-	int ret;
 
 	bridge->conf.vendor =
 		cpu_to_le16(advk_readl(pcie, PCIE_CORE_DEV_ID_REG) & 0xffff);
@@ -842,19 +841,14 @@ static int advk_sw_pci_bridge_init(struct advk_pcie *pcie)
 	/* Support interrupt A for MSI feature */
 	bridge->conf.intpin = PCIE_CORE_INT_A_ASSERT_ENABLE;
 
+	/* Indicates supports for Completion Retry Status */
+	bridge->pcie_conf.rootcap = cpu_to_le16(PCI_EXP_RTCAP_CRSVIS);
+
 	bridge->has_pcie = true;
 	bridge->data = pcie;
 	bridge->ops = &advk_pci_bridge_emul_ops;
 
-	/* PCIe config space can be initialized after pci_bridge_emul_init() */
-	ret = pci_bridge_emul_init(bridge, 0);
-	if (ret < 0)
-		return ret;
-
-	/* Indicates supports for Completion Retry Status */
-	bridge->pcie_conf.rootcap = cpu_to_le16(PCI_EXP_RTCAP_CRSVIS);
-
-	return 0;
+	return pci_bridge_emul_init(bridge, 0);
 }
 
 static bool advk_pcie_valid_device(struct advk_pcie *pcie, struct pci_bus *bus,
-- 
2.32.0

[PATCH v2 11/13] PCI: aardvark: Fix link training

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

Fix multiple link training issues in aardvark driver. The main reason of
these issues was misunderstanding of what certain registers do, since their
names and comments were misleading: before commit 96be36dbffac ("PCI:
aardvark: Replace custom macros by standard linux/pci_regs.h macros"), the
pci-aardvark.c driver used custom macros for accessing standard PCIe Root
Bridge registers, and misleading comments did not help to understand what
the code was really doing.

After doing more tests and experiments I've come to the conclusion that the
SPEED_GEN register in aardvark sets the PCIe revision / generation
compliance and forces maximal link speed. Both GEN3 and GEN2 values set the
read-only PCI_EXP_FLAGS_VERS bits (PCIe capabilities version of Root
Bridge) to value 2, while GEN1 value sets PCI_EXP_FLAGS_VERS to 1, which
matches with PCI Express specifications revisions 3, 2 and 1 respectively.
Changing SPEED_GEN also sets the read-only bits PCI_EXP_LNKCAP_SLS and
PCI_EXP_LNKCAP2_SLS to corresponding speed.

(Note that PCI Express rev 1 specification does not define PCI_EXP_LNKCAP2
 and PCI_EXP_LNKCTL2 registers and when SPEED_GEN is set to GEN1 (which
 also sets PCI_EXP_FLAGS_VERS set to 1), lspci cannot access
 PCI_EXP_LNKCAP2 and PCI_EXP_LNKCTL2 registers.)

Changing PCIe link speed can be done via PCI_EXP_LNKCTL2_TLS bits of
PCI_EXP_LNKCTL2 register. Armada 3700 Functional Specifications says that
the default value of PCI_EXP_LNKCTL2_TLS is based on SPEED_GEN value, but
tests showed that the default value is always 8.0 GT/s, independently of
speed set by SPEED_GEN. So after setting SPEED_GEN, we must also set value
in PCI_EXP_LNKCTL2 register via PCI_EXP_LNKCTL2_TLS bits.

Triggering PCI_EXP_LNKCTL_RL bit immediately after setting LINK_TRAINING_EN
bit actually doesn't do anything. Tests have shown that a delay is needed
after enabling LINK_TRAINING_EN bit. As triggering PCI_EXP_LNKCTL_RL
currently does nothing, remove it.

Commit 43fc679ced18 ("PCI: aardvark: Improve link training") introduced
code which sets SPEED_GEN register based on negotiated link speed from
PCI_EXP_LNKSTA_CLS bits of PCI_EXP_LNKSTA register. This code was added to
fix detection of Compex WLE900VX (Atheros QCA9880) WiFi GEN1 PCIe cards, as
otherwise these cards were "invisible" on PCIe bus (probably because they
crashed). But apparently more people reported the same issues with these
cards also with other PCIe controllers [1] and I was able to reproduce this
issue also with other "noname" WiFi cards based on Atheros QCA9890 chip
(with the same PCI vendor/device ids as Atheros QCA9880). So this is not an
issue in aardvark but rather an issue in Atheros QCA98xx chips. Also, this
issue only exists if the kernel is compiled with PCIe ASPM support, and a
generic workaround for this is to change PCIe Bridge to 2.5 GT/s link speed
via PCI_EXP_LNKCTL2_TLS_2_5GT bits in PCI_EXP_LNKCTL2 register [2], before
triggering PCI_EXP_LNKCTL_RL bit. This workaround also works when SPEED_GEN
is set to value GEN2 (5 GT/s). So remove this hack completely in the
aardvark driver and always set SPEED_GEN to value from 'max-link-speed' DT
property. Fix for Atheros QCA98xx chips is handled separately by patch [2].

These two things (code for triggering PCI_EXP_LNKCTL_RL bit and changing
SPEED_GEN value) also explain why commit 6964494582f5 ("PCI: aardvark:
Train link immediately after enabling training") somehow fixed detection of
those problematic Compex cards with Atheros chips: if triggering link
retraining (via PCI_EXP_LNKCTL_RL bit) was done immediately after enabling
link training (via LINK_TRAINING_EN), it did nothing. If there was a
specific delay, aardvark HW already initialized PCIe link and therefore
triggering link retraining caused the above issue. Compex cards triggered
link down event and disappeared from the PCIe bus.

Commit f4c7d053d7f7 ("PCI: aardvark: Wait for endpoint to be ready before
training link") added 100ms sleep before calling 'Start link training'
command and explained that it is a requirement of PCI Express
specification. But the code after this 100ms sleep was not doing 'Start
link training', rather it triggered PCI_EXP_LNKCTL_RL bit via PCIe Root
Bridge to put link into Recovery state.

The required delay after fundamental reset is already done in function
advk_pcie_wait_for_link() which also checks whether PCIe link is up.
So after removing the code which triggers PCI_EXP_LNKCTL_RL bit on PCIe
Root Bridge, there is no need to wait 100ms again. Remove the extra
msleep() call and update comment about the delay required by the PCI
Express specification.

According to Marvell Armada 3700 Functional Specifications, Link training
should be enabled via aardvark register LINK_TRAINING_EN after selecting
PCIe generation and x1 lane. There is no need to disable it prior resetting
card via PERST# signal. This disabling code was introduced in commit
5169a9851daa ("PCI: aardvark: Issue PERST via GPIO") as a workaround for
some Atheros cards. It turns out that this also is Atheros specific issue
and affects any PCIe controller, not only aardvark. Moreover this Atheros
issue was triggered by juggling with PCI_EXP_LNKCTL_RL, LINK_TRAINING_EN
and SPEED_GEN bits interleaved with sleeps. Now, after removing triggering
PCI_EXP_LNKCTL_RL, there is no need to explicitly disable LINK_TRAINING_EN
bit. So remove this code too. The problematic Compex cards described in
previous git commits are correctly detected in advk_pcie_train_link()
function even after applying all these changes.

Note that with this patch, and also prior this patch, some NVMe disks which
support PCIe GEN3 with 8 GT/s speed are negotiated only at the lowest link
speed 2.5 GT/s, independently of SPEED_GEN value. After manually triggering
PCI_EXP_LNKCTL_RL bit (e.g. from userspace via setpci), these NVMe disks
change link speed to 5 GT/s when SPEED_GEN was configured to GEN2. This
issue first needs to be properly investigated. I will send a fix in the
future.

On the other hand, some other GEN2 PCIe cards with 5 GT/s speed are
autonomously by HW autonegotiated at full 5 GT/s speed without need of any
software interaction.

Armada 3700 Functional Specifications describes the following steps for
link training: set SPEED_GEN to GEN2, enable LINK_TRAINING_EN, poll until
link training is complete, trigger PCI_EXP_LNKCTL_RL, poll until signal
rate is 5 GT/s, poll until link training is complete, enable ASPM L0s.

The requirement for triggering PCI_EXP_LNKCTL_RL can be explained by the
need to achieve 5 GT/s speed (as changing link speed is done by throw to
recovery state entered by PCI_EXP_LNKCTL_RL) or maybe as a part of enabling
ASPM L0s (but in this case ASPM L0s should have been enabled prior
PCI_EXP_LNKCTL_RL).

It is unknown why the original pci-aardvark.c driver was triggering
PCI_EXP_LNKCTL_RL bit before waiting for the link to be up. This does not
align with neither PCIe base specifications nor with Armada 3700 Functional
Specification. (Note that in older versions of aardvark, this bit was
called incorrectly PCIE_CORE_LINK_TRAINING, so this may be the reason.)

It is also unknown why Armada 3700 Functional Specification says that it is
needed to trigger PCI_EXP_LNKCTL_RL for GEN2 mode, as according to PCIe
base specification 5 GT/s speed negotiation is supposed to be entirely
autonomous, even if initial speed is 2.5 GT/s.

[1] - https://lore.kernel.org/linux-pci/87h7l8axqp.fsf@toke.dk/
[2] - https://lore.kernel.org/linux-pci/20210326124326.21163-1-pali@kernel.org/

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: stable@vger.kernel.org # f4c7d053d7f7 ("PCI: aardvark: Wait for endpoint to be ready before training link")
Cc: stable@vger.kernel.org # 6964494582f5 ("PCI: aardvark: Train link immediately after enabling training")
Cc: stable@vger.kernel.org # 43fc679ced18 ("PCI: aardvark: Improve link training")
Cc: stable@vger.kernel.org # 5169a9851daa ("PCI: aardvark: Issue PERST via GPIO")
Cc: stable@vger.kernel.org # 96be36dbffac ("PCI: aardvark: Replace custom macros by standard linux/pci_regs.h macros")
Cc: stable@vger.kernel.org # d0c6a3475b03 ("PCI: aardvark: Move PCIe reset card code to advk_pcie_train_link()")
Cc: stable@vger.kernel.org # 1d1cd163d0de ("PCI: aardvark: Update comment about disabling link training")
---
 drivers/pci/controller/pci-aardvark.c | 117 ++++++++------------------
 1 file changed, 34 insertions(+), 83 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 9c509d5a9afa..2c66cdbb8dd6 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -258,11 +258,6 @@ static inline u32 advk_readl(struct advk_pcie *pcie, u64 reg)
 	return readl(pcie->base + reg);
 }
 
-static inline u16 advk_read16(struct advk_pcie *pcie, u64 reg)
-{
-	return advk_readl(pcie, (reg & ~0x3)) >> ((reg & 0x3) * 8);
-}
-
 static int advk_pcie_link_up(struct advk_pcie *pcie)
 {
 	u32 val, ltssm_state;
@@ -300,23 +295,9 @@ static void advk_pcie_wait_for_retrain(struct advk_pcie *pcie)
 
 static void advk_pcie_issue_perst(struct advk_pcie *pcie)
 {
-	u32 reg;
-
 	if (!pcie->reset_gpio)
 		return;
 
-	/*
-	 * As required by PCI Express spec (PCI Express Base Specification, REV.
-	 * 4.0 PCI Express, February 19 2014, 6.6.1 Conventional Reset) a delay
-	 * for at least 100ms after de-asserting PERST# signal is needed before
-	 * link training is enabled. So ensure that link training is disabled
-	 * prior de-asserting PERST# signal to fulfill that PCI Express spec
-	 * requirement.
-	 */
-	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
-	reg &= ~LINK_TRAINING_EN;
-	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
-
 	/* 10ms delay is needed for some cards */
 	dev_info(&pcie->pdev->dev, "issuing PERST via reset GPIO for 10ms\n");
 	gpiod_set_value_cansleep(pcie->reset_gpio, 1);
@@ -324,53 +305,46 @@ static void advk_pcie_issue_perst(struct advk_pcie *pcie)
 	gpiod_set_value_cansleep(pcie->reset_gpio, 0);
 }
 
-static int advk_pcie_train_at_gen(struct advk_pcie *pcie, int gen)
+static void advk_pcie_train_link(struct advk_pcie *pcie)
 {
-	int ret, neg_gen;
+	struct device *dev = &pcie->pdev->dev;
 	u32 reg;
+	int ret;
 
-	/* Setup link speed */
+	/*
+	 * Setup PCIe rev / gen compliance based on device tree property
+	 * 'max-link-speed' which also forces maximal link speed.
+	 */
 	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
 	reg &= ~PCIE_GEN_SEL_MSK;
-	if (gen == 3)
+	if (pcie->link_gen == 3)
 		reg |= SPEED_GEN_3;
-	else if (gen == 2)
+	else if (pcie->link_gen == 2)
 		reg |= SPEED_GEN_2;
 	else
 		reg |= SPEED_GEN_1;
 	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
 
 	/*
-	 * Enable link training. This is not needed in every call to this
-	 * function, just once suffices, but it does not break anything either.
+	 * Set maximal link speed value also into PCIe Link Control 2 register.
+	 * Armada 3700 Functional Specification says that default value is based
+	 * on SPEED_GEN but tests showed that default value is always 8.0 GT/s.
 	 */
+	reg = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKCTL2);
+	reg &= ~PCI_EXP_LNKCTL2_TLS;
+	if (pcie->link_gen == 3)
+		reg |= PCI_EXP_LNKCTL2_TLS_8_0GT;
+	else if (pcie->link_gen == 2)
+		reg |= PCI_EXP_LNKCTL2_TLS_5_0GT;
+	else
+		reg |= PCI_EXP_LNKCTL2_TLS_2_5GT;
+	advk_writel(pcie, reg, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKCTL2);
+
+	/* Enable link training after selecting PCIe generation */
 	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
 	reg |= LINK_TRAINING_EN;
 	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
 
-	/*
-	 * Start link training immediately after enabling it.
-	 * This solves problems for some buggy cards.
-	 */
-	reg = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKCTL);
-	reg |= PCI_EXP_LNKCTL_RL;
-	advk_writel(pcie, reg, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKCTL);
-
-	ret = advk_pcie_wait_for_link(pcie);
-	if (ret)
-		return ret;
-
-	reg = advk_read16(pcie, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKSTA);
-	neg_gen = reg & PCI_EXP_LNKSTA_CLS;
-
-	return neg_gen;
-}
-
-static void advk_pcie_train_link(struct advk_pcie *pcie)
-{
-	struct device *dev = &pcie->pdev->dev;
-	int neg_gen = -1, gen;
-
 	/*
 	 * Reset PCIe card via PERST# signal. Some cards are not detected
 	 * during link training when they are in some non-initial state.
@@ -381,41 +355,18 @@ static void advk_pcie_train_link(struct advk_pcie *pcie)
 	 * PERST# signal could have been asserted by pinctrl subsystem before
 	 * probe() callback has been called or issued explicitly by reset gpio
 	 * function advk_pcie_issue_perst(), making the endpoint going into
-	 * fundamental reset. As required by PCI Express spec a delay for at
-	 * least 100ms after such a reset before link training is needed.
-	 */
-	msleep(PCI_PM_D3COLD_WAIT);
-
-	/*
-	 * Try link training at link gen specified by device tree property
-	 * 'max-link-speed'. If this fails, iteratively train at lower gen.
-	 */
-	for (gen = pcie->link_gen; gen > 0; --gen) {
-		neg_gen = advk_pcie_train_at_gen(pcie, gen);
-		if (neg_gen > 0)
-			break;
-	}
-
-	if (neg_gen < 0)
-		goto err;
-
-	/*
-	 * After successful training if negotiated gen is lower than requested,
-	 * train again on negotiated gen. This solves some stability issues for
-	 * some buggy gen1 cards.
+	 * fundamental reset. As required by PCI Express spec (PCI Express
+	 * Base Specification, REV. 4.0 PCI Express, February 19 2014, 6.6.1
+	 * Conventional Reset) a delay for at least 100ms after such a reset
+	 * before sending a Configuration Request to the device is needed.
+	 * So wait until PCIe link is up. Function advk_pcie_wait_for_link()
+	 * waits for link at least 900ms.
 	 */
-	if (neg_gen < gen) {
-		gen = neg_gen;
-		neg_gen = advk_pcie_train_at_gen(pcie, gen);
-	}
-
-	if (neg_gen == gen) {
-		dev_info(dev, "link up at gen %i\n", gen);
-		return;
-	}
-
-err:
-	dev_err(dev, "link never came up\n");
+	ret = advk_pcie_wait_for_link(pcie);
+	if (ret < 0)
+		dev_err(dev, "link never came up\n");
+	else
+		dev_info(dev, "link up\n");
 }
 
 /*
-- 
2.32.0

Re: [PATCH v2 11/13] PCI: aardvark: Fix link training

[Lorenzo Pieralisi]

On Tue, Oct 05, 2021 at 08:09:50PM +0200, Marek Behún wrote:
> From: Pali Rohár <pali@kernel.org>
> 
> Fix multiple link training issues in aardvark driver. The main reason of
> these issues was misunderstanding of what certain registers do, since their
> names and comments were misleading: before commit 96be36dbffac ("PCI:
> aardvark: Replace custom macros by standard linux/pci_regs.h macros"), the
> pci-aardvark.c driver used custom macros for accessing standard PCIe Root
> Bridge registers, and misleading comments did not help to understand what
> the code was really doing.
> 
> After doing more tests and experiments I've come to the conclusion that the
> SPEED_GEN register in aardvark sets the PCIe revision / generation
> compliance and forces maximal link speed. Both GEN3 and GEN2 values set the
> read-only PCI_EXP_FLAGS_VERS bits (PCIe capabilities version of Root
> Bridge) to value 2, while GEN1 value sets PCI_EXP_FLAGS_VERS to 1, which
> matches with PCI Express specifications revisions 3, 2 and 1 respectively.
> Changing SPEED_GEN also sets the read-only bits PCI_EXP_LNKCAP_SLS and
> PCI_EXP_LNKCAP2_SLS to corresponding speed.
> 
> (Note that PCI Express rev 1 specification does not define PCI_EXP_LNKCAP2
>  and PCI_EXP_LNKCTL2 registers and when SPEED_GEN is set to GEN1 (which
>  also sets PCI_EXP_FLAGS_VERS set to 1), lspci cannot access
>  PCI_EXP_LNKCAP2 and PCI_EXP_LNKCTL2 registers.)
> 
> Changing PCIe link speed can be done via PCI_EXP_LNKCTL2_TLS bits of
> PCI_EXP_LNKCTL2 register. Armada 3700 Functional Specifications says that
> the default value of PCI_EXP_LNKCTL2_TLS is based on SPEED_GEN value, but
> tests showed that the default value is always 8.0 GT/s, independently of
> speed set by SPEED_GEN. So after setting SPEED_GEN, we must also set value
> in PCI_EXP_LNKCTL2 register via PCI_EXP_LNKCTL2_TLS bits.
> 
> Triggering PCI_EXP_LNKCTL_RL bit immediately after setting LINK_TRAINING_EN
> bit actually doesn't do anything. Tests have shown that a delay is needed
> after enabling LINK_TRAINING_EN bit. As triggering PCI_EXP_LNKCTL_RL
> currently does nothing, remove it.
> 
> Commit 43fc679ced18 ("PCI: aardvark: Improve link training") introduced
> code which sets SPEED_GEN register based on negotiated link speed from
> PCI_EXP_LNKSTA_CLS bits of PCI_EXP_LNKSTA register. This code was added to
> fix detection of Compex WLE900VX (Atheros QCA9880) WiFi GEN1 PCIe cards, as
> otherwise these cards were "invisible" on PCIe bus (probably because they
> crashed). But apparently more people reported the same issues with these
> cards also with other PCIe controllers [1] and I was able to reproduce this
> issue also with other "noname" WiFi cards based on Atheros QCA9890 chip
> (with the same PCI vendor/device ids as Atheros QCA9880). So this is not an
> issue in aardvark but rather an issue in Atheros QCA98xx chips. Also, this
> issue only exists if the kernel is compiled with PCIe ASPM support, and a
> generic workaround for this is to change PCIe Bridge to 2.5 GT/s link speed
> via PCI_EXP_LNKCTL2_TLS_2_5GT bits in PCI_EXP_LNKCTL2 register [2], before
> triggering PCI_EXP_LNKCTL_RL bit. This workaround also works when SPEED_GEN
> is set to value GEN2 (5 GT/s). So remove this hack completely in the
> aardvark driver and always set SPEED_GEN to value from 'max-link-speed' DT
> property. Fix for Atheros QCA98xx chips is handled separately by patch [2].
> 
> These two things (code for triggering PCI_EXP_LNKCTL_RL bit and changing
> SPEED_GEN value) also explain why commit 6964494582f5 ("PCI: aardvark:
> Train link immediately after enabling training") somehow fixed detection of
> those problematic Compex cards with Atheros chips: if triggering link
> retraining (via PCI_EXP_LNKCTL_RL bit) was done immediately after enabling
> link training (via LINK_TRAINING_EN), it did nothing. If there was a
> specific delay, aardvark HW already initialized PCIe link and therefore
> triggering link retraining caused the above issue. Compex cards triggered
> link down event and disappeared from the PCIe bus.
> 
> Commit f4c7d053d7f7 ("PCI: aardvark: Wait for endpoint to be ready before
> training link") added 100ms sleep before calling 'Start link training'
> command and explained that it is a requirement of PCI Express
> specification. But the code after this 100ms sleep was not doing 'Start
> link training', rather it triggered PCI_EXP_LNKCTL_RL bit via PCIe Root
> Bridge to put link into Recovery state.
> 
> The required delay after fundamental reset is already done in function
> advk_pcie_wait_for_link() which also checks whether PCIe link is up.
> So after removing the code which triggers PCI_EXP_LNKCTL_RL bit on PCIe
> Root Bridge, there is no need to wait 100ms again. Remove the extra
> msleep() call and update comment about the delay required by the PCI
> Express specification.
> 
> According to Marvell Armada 3700 Functional Specifications, Link training
> should be enabled via aardvark register LINK_TRAINING_EN after selecting
> PCIe generation and x1 lane. There is no need to disable it prior resetting
> card via PERST# signal. This disabling code was introduced in commit
> 5169a9851daa ("PCI: aardvark: Issue PERST via GPIO") as a workaround for
> some Atheros cards. It turns out that this also is Atheros specific issue
> and affects any PCIe controller, not only aardvark. Moreover this Atheros
> issue was triggered by juggling with PCI_EXP_LNKCTL_RL, LINK_TRAINING_EN
> and SPEED_GEN bits interleaved with sleeps. Now, after removing triggering
> PCI_EXP_LNKCTL_RL, there is no need to explicitly disable LINK_TRAINING_EN
> bit. So remove this code too. The problematic Compex cards described in
> previous git commits are correctly detected in advk_pcie_train_link()
> function even after applying all these changes.
> 
> Note that with this patch, and also prior this patch, some NVMe disks which
> support PCIe GEN3 with 8 GT/s speed are negotiated only at the lowest link
> speed 2.5 GT/s, independently of SPEED_GEN value. After manually triggering
> PCI_EXP_LNKCTL_RL bit (e.g. from userspace via setpci), these NVMe disks
> change link speed to 5 GT/s when SPEED_GEN was configured to GEN2. This
> issue first needs to be properly investigated. I will send a fix in the
> future.
> 
> On the other hand, some other GEN2 PCIe cards with 5 GT/s speed are
> autonomously by HW autonegotiated at full 5 GT/s speed without need of any
> software interaction.
> 
> Armada 3700 Functional Specifications describes the following steps for
> link training: set SPEED_GEN to GEN2, enable LINK_TRAINING_EN, poll until
> link training is complete, trigger PCI_EXP_LNKCTL_RL, poll until signal
> rate is 5 GT/s, poll until link training is complete, enable ASPM L0s.
> 
> The requirement for triggering PCI_EXP_LNKCTL_RL can be explained by the
> need to achieve 5 GT/s speed (as changing link speed is done by throw to
> recovery state entered by PCI_EXP_LNKCTL_RL) or maybe as a part of enabling
> ASPM L0s (but in this case ASPM L0s should have been enabled prior
> PCI_EXP_LNKCTL_RL).
> 
> It is unknown why the original pci-aardvark.c driver was triggering
> PCI_EXP_LNKCTL_RL bit before waiting for the link to be up. This does not
> align with neither PCIe base specifications nor with Armada 3700 Functional
> Specification. (Note that in older versions of aardvark, this bit was
> called incorrectly PCIE_CORE_LINK_TRAINING, so this may be the reason.)
> 
> It is also unknown why Armada 3700 Functional Specification says that it is
> needed to trigger PCI_EXP_LNKCTL_RL for GEN2 mode, as according to PCIe
> base specification 5 GT/s speed negotiation is supposed to be entirely
> autonomous, even if initial speed is 2.5 GT/s.
> 
> [1] - https://lore.kernel.org/linux-pci/87h7l8axqp.fsf@toke.dk/
> [2] - https://lore.kernel.org/linux-pci/20210326124326.21163-1-pali@kernel.org/
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>
> Reviewed-by: Marek Behún <kabel@kernel.org>
> Signed-off-by: Marek Behún <kabel@kernel.org>
> Cc: stable@vger.kernel.org # f4c7d053d7f7 ("PCI: aardvark: Wait for endpoint to be ready before training link")
> Cc: stable@vger.kernel.org # 6964494582f5 ("PCI: aardvark: Train link immediately after enabling training")
> Cc: stable@vger.kernel.org # 43fc679ced18 ("PCI: aardvark: Improve link training")
> Cc: stable@vger.kernel.org # 5169a9851daa ("PCI: aardvark: Issue PERST via GPIO")
> Cc: stable@vger.kernel.org # 96be36dbffac ("PCI: aardvark: Replace custom macros by standard linux/pci_regs.h macros")
> Cc: stable@vger.kernel.org # d0c6a3475b03 ("PCI: aardvark: Move PCIe reset card code to advk_pcie_train_link()")
> Cc: stable@vger.kernel.org # 1d1cd163d0de ("PCI: aardvark: Update comment about disabling link training")
> ---
>  drivers/pci/controller/pci-aardvark.c | 117 ++++++++------------------
>  1 file changed, 34 insertions(+), 83 deletions(-)

This is a very convoluted fix; it is well explained but the number
of patches going into stable and the complexity of it make me ask
how confident you are this won't trigger any regressions.

It is just a heads-up to make you think whether it is better to
hold the stable tags till we are confident enough.

Please let me know.

Thanks,
Lorenzo

> 
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 9c509d5a9afa..2c66cdbb8dd6 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -258,11 +258,6 @@ static inline u32 advk_readl(struct advk_pcie *pcie, u64 reg)
>  	return readl(pcie->base + reg);
>  }
>  
> -static inline u16 advk_read16(struct advk_pcie *pcie, u64 reg)
> -{
> -	return advk_readl(pcie, (reg & ~0x3)) >> ((reg & 0x3) * 8);
> -}
> -
>  static int advk_pcie_link_up(struct advk_pcie *pcie)
>  {
>  	u32 val, ltssm_state;
> @@ -300,23 +295,9 @@ static void advk_pcie_wait_for_retrain(struct advk_pcie *pcie)
>  
>  static void advk_pcie_issue_perst(struct advk_pcie *pcie)
>  {
> -	u32 reg;
> -
>  	if (!pcie->reset_gpio)
>  		return;
>  
> -	/*
> -	 * As required by PCI Express spec (PCI Express Base Specification, REV.
> -	 * 4.0 PCI Express, February 19 2014, 6.6.1 Conventional Reset) a delay
> -	 * for at least 100ms after de-asserting PERST# signal is needed before
> -	 * link training is enabled. So ensure that link training is disabled
> -	 * prior de-asserting PERST# signal to fulfill that PCI Express spec
> -	 * requirement.
> -	 */
> -	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
> -	reg &= ~LINK_TRAINING_EN;
> -	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
> -
>  	/* 10ms delay is needed for some cards */
>  	dev_info(&pcie->pdev->dev, "issuing PERST via reset GPIO for 10ms\n");
>  	gpiod_set_value_cansleep(pcie->reset_gpio, 1);
> @@ -324,53 +305,46 @@ static void advk_pcie_issue_perst(struct advk_pcie *pcie)
>  	gpiod_set_value_cansleep(pcie->reset_gpio, 0);
>  }
>  
> -static int advk_pcie_train_at_gen(struct advk_pcie *pcie, int gen)
> +static void advk_pcie_train_link(struct advk_pcie *pcie)
>  {
> -	int ret, neg_gen;
> +	struct device *dev = &pcie->pdev->dev;
>  	u32 reg;
> +	int ret;
>  
> -	/* Setup link speed */
> +	/*
> +	 * Setup PCIe rev / gen compliance based on device tree property
> +	 * 'max-link-speed' which also forces maximal link speed.
> +	 */
>  	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
>  	reg &= ~PCIE_GEN_SEL_MSK;
> -	if (gen == 3)
> +	if (pcie->link_gen == 3)
>  		reg |= SPEED_GEN_3;
> -	else if (gen == 2)
> +	else if (pcie->link_gen == 2)
>  		reg |= SPEED_GEN_2;
>  	else
>  		reg |= SPEED_GEN_1;
>  	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
>  
>  	/*
> -	 * Enable link training. This is not needed in every call to this
> -	 * function, just once suffices, but it does not break anything either.
> +	 * Set maximal link speed value also into PCIe Link Control 2 register.
> +	 * Armada 3700 Functional Specification says that default value is based
> +	 * on SPEED_GEN but tests showed that default value is always 8.0 GT/s.
>  	 */
> +	reg = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKCTL2);
> +	reg &= ~PCI_EXP_LNKCTL2_TLS;
> +	if (pcie->link_gen == 3)
> +		reg |= PCI_EXP_LNKCTL2_TLS_8_0GT;
> +	else if (pcie->link_gen == 2)
> +		reg |= PCI_EXP_LNKCTL2_TLS_5_0GT;
> +	else
> +		reg |= PCI_EXP_LNKCTL2_TLS_2_5GT;
> +	advk_writel(pcie, reg, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKCTL2);
> +
> +	/* Enable link training after selecting PCIe generation */
>  	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
>  	reg |= LINK_TRAINING_EN;
>  	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
>  
> -	/*
> -	 * Start link training immediately after enabling it.
> -	 * This solves problems for some buggy cards.
> -	 */
> -	reg = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKCTL);
> -	reg |= PCI_EXP_LNKCTL_RL;
> -	advk_writel(pcie, reg, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKCTL);
> -
> -	ret = advk_pcie_wait_for_link(pcie);
> -	if (ret)
> -		return ret;
> -
> -	reg = advk_read16(pcie, PCIE_CORE_PCIEXP_CAP + PCI_EXP_LNKSTA);
> -	neg_gen = reg & PCI_EXP_LNKSTA_CLS;
> -
> -	return neg_gen;
> -}
> -
> -static void advk_pcie_train_link(struct advk_pcie *pcie)
> -{
> -	struct device *dev = &pcie->pdev->dev;
> -	int neg_gen = -1, gen;
> -
>  	/*
>  	 * Reset PCIe card via PERST# signal. Some cards are not detected
>  	 * during link training when they are in some non-initial state.
> @@ -381,41 +355,18 @@ static void advk_pcie_train_link(struct advk_pcie *pcie)
>  	 * PERST# signal could have been asserted by pinctrl subsystem before
>  	 * probe() callback has been called or issued explicitly by reset gpio
>  	 * function advk_pcie_issue_perst(), making the endpoint going into
> -	 * fundamental reset. As required by PCI Express spec a delay for at
> -	 * least 100ms after such a reset before link training is needed.
> -	 */
> -	msleep(PCI_PM_D3COLD_WAIT);
> -
> -	/*
> -	 * Try link training at link gen specified by device tree property
> -	 * 'max-link-speed'. If this fails, iteratively train at lower gen.
> -	 */
> -	for (gen = pcie->link_gen; gen > 0; --gen) {
> -		neg_gen = advk_pcie_train_at_gen(pcie, gen);
> -		if (neg_gen > 0)
> -			break;
> -	}
> -
> -	if (neg_gen < 0)
> -		goto err;
> -
> -	/*
> -	 * After successful training if negotiated gen is lower than requested,
> -	 * train again on negotiated gen. This solves some stability issues for
> -	 * some buggy gen1 cards.
> +	 * fundamental reset. As required by PCI Express spec (PCI Express
> +	 * Base Specification, REV. 4.0 PCI Express, February 19 2014, 6.6.1
> +	 * Conventional Reset) a delay for at least 100ms after such a reset
> +	 * before sending a Configuration Request to the device is needed.
> +	 * So wait until PCIe link is up. Function advk_pcie_wait_for_link()
> +	 * waits for link at least 900ms.
>  	 */
> -	if (neg_gen < gen) {
> -		gen = neg_gen;
> -		neg_gen = advk_pcie_train_at_gen(pcie, gen);
> -	}
> -
> -	if (neg_gen == gen) {
> -		dev_info(dev, "link up at gen %i\n", gen);
> -		return;
> -	}
> -
> -err:
> -	dev_err(dev, "link never came up\n");
> +	ret = advk_pcie_wait_for_link(pcie);
> +	if (ret < 0)
> +		dev_err(dev, "link never came up\n");
> +	else
> +		dev_info(dev, "link up\n");
>  }
>  
>  /*
> -- 
> 2.32.0
> 

Re: [PATCH v2 11/13] PCI: aardvark: Fix link training

[Marek Behún]

On Thu, 7 Oct 2021 12:55:22 +0100
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote:

> On Tue, Oct 05, 2021 at 08:09:50PM +0200, Marek Behún wrote:
> > From: Pali Rohár <pali@kernel.org>
> > 
> > Fix multiple link training issues in aardvark driver. The main reason of
> > these issues was misunderstanding of what certain registers do, since their
> > names and comments were misleading: before commit 96be36dbffac ("PCI:
> > aardvark: Replace custom macros by standard linux/pci_regs.h macros"), the
> > pci-aardvark.c driver used custom macros for accessing standard PCIe Root
> > Bridge registers, and misleading comments did not help to understand what
> > the code was really doing.
> > 
> > After doing more tests and experiments I've come to the conclusion that the
> > SPEED_GEN register in aardvark sets the PCIe revision / generation
> > compliance and forces maximal link speed. Both GEN3 and GEN2 values set the
> > read-only PCI_EXP_FLAGS_VERS bits (PCIe capabilities version of Root
> > Bridge) to value 2, while GEN1 value sets PCI_EXP_FLAGS_VERS to 1, which
> > matches with PCI Express specifications revisions 3, 2 and 1 respectively.
> > Changing SPEED_GEN also sets the read-only bits PCI_EXP_LNKCAP_SLS and
> > PCI_EXP_LNKCAP2_SLS to corresponding speed.
> > 
> > (Note that PCI Express rev 1 specification does not define PCI_EXP_LNKCAP2
> >  and PCI_EXP_LNKCTL2 registers and when SPEED_GEN is set to GEN1 (which
> >  also sets PCI_EXP_FLAGS_VERS set to 1), lspci cannot access
> >  PCI_EXP_LNKCAP2 and PCI_EXP_LNKCTL2 registers.)
> > 
> > Changing PCIe link speed can be done via PCI_EXP_LNKCTL2_TLS bits of
> > PCI_EXP_LNKCTL2 register. Armada 3700 Functional Specifications says that
> > the default value of PCI_EXP_LNKCTL2_TLS is based on SPEED_GEN value, but
> > tests showed that the default value is always 8.0 GT/s, independently of
> > speed set by SPEED_GEN. So after setting SPEED_GEN, we must also set value
> > in PCI_EXP_LNKCTL2 register via PCI_EXP_LNKCTL2_TLS bits.
> > 
> > Triggering PCI_EXP_LNKCTL_RL bit immediately after setting LINK_TRAINING_EN
> > bit actually doesn't do anything. Tests have shown that a delay is needed
> > after enabling LINK_TRAINING_EN bit. As triggering PCI_EXP_LNKCTL_RL
> > currently does nothing, remove it.
> > 
> > Commit 43fc679ced18 ("PCI: aardvark: Improve link training") introduced
> > code which sets SPEED_GEN register based on negotiated link speed from
> > PCI_EXP_LNKSTA_CLS bits of PCI_EXP_LNKSTA register. This code was added to
> > fix detection of Compex WLE900VX (Atheros QCA9880) WiFi GEN1 PCIe cards, as
> > otherwise these cards were "invisible" on PCIe bus (probably because they
> > crashed). But apparently more people reported the same issues with these
> > cards also with other PCIe controllers [1] and I was able to reproduce this
> > issue also with other "noname" WiFi cards based on Atheros QCA9890 chip
> > (with the same PCI vendor/device ids as Atheros QCA9880). So this is not an
> > issue in aardvark but rather an issue in Atheros QCA98xx chips. Also, this
> > issue only exists if the kernel is compiled with PCIe ASPM support, and a
> > generic workaround for this is to change PCIe Bridge to 2.5 GT/s link speed
> > via PCI_EXP_LNKCTL2_TLS_2_5GT bits in PCI_EXP_LNKCTL2 register [2], before
> > triggering PCI_EXP_LNKCTL_RL bit. This workaround also works when SPEED_GEN
> > is set to value GEN2 (5 GT/s). So remove this hack completely in the
> > aardvark driver and always set SPEED_GEN to value from 'max-link-speed' DT
> > property. Fix for Atheros QCA98xx chips is handled separately by patch [2].
> > 
> > These two things (code for triggering PCI_EXP_LNKCTL_RL bit and changing
> > SPEED_GEN value) also explain why commit 6964494582f5 ("PCI: aardvark:
> > Train link immediately after enabling training") somehow fixed detection of
> > those problematic Compex cards with Atheros chips: if triggering link
> > retraining (via PCI_EXP_LNKCTL_RL bit) was done immediately after enabling
> > link training (via LINK_TRAINING_EN), it did nothing. If there was a
> > specific delay, aardvark HW already initialized PCIe link and therefore
> > triggering link retraining caused the above issue. Compex cards triggered
> > link down event and disappeared from the PCIe bus.
> > 
> > Commit f4c7d053d7f7 ("PCI: aardvark: Wait for endpoint to be ready before
> > training link") added 100ms sleep before calling 'Start link training'
> > command and explained that it is a requirement of PCI Express
> > specification. But the code after this 100ms sleep was not doing 'Start
> > link training', rather it triggered PCI_EXP_LNKCTL_RL bit via PCIe Root
> > Bridge to put link into Recovery state.
> > 
> > The required delay after fundamental reset is already done in function
> > advk_pcie_wait_for_link() which also checks whether PCIe link is up.
> > So after removing the code which triggers PCI_EXP_LNKCTL_RL bit on PCIe
> > Root Bridge, there is no need to wait 100ms again. Remove the extra
> > msleep() call and update comment about the delay required by the PCI
> > Express specification.
> > 
> > According to Marvell Armada 3700 Functional Specifications, Link training
> > should be enabled via aardvark register LINK_TRAINING_EN after selecting
> > PCIe generation and x1 lane. There is no need to disable it prior resetting
> > card via PERST# signal. This disabling code was introduced in commit
> > 5169a9851daa ("PCI: aardvark: Issue PERST via GPIO") as a workaround for
> > some Atheros cards. It turns out that this also is Atheros specific issue
> > and affects any PCIe controller, not only aardvark. Moreover this Atheros
> > issue was triggered by juggling with PCI_EXP_LNKCTL_RL, LINK_TRAINING_EN
> > and SPEED_GEN bits interleaved with sleeps. Now, after removing triggering
> > PCI_EXP_LNKCTL_RL, there is no need to explicitly disable LINK_TRAINING_EN
> > bit. So remove this code too. The problematic Compex cards described in
> > previous git commits are correctly detected in advk_pcie_train_link()
> > function even after applying all these changes.
> > 
> > Note that with this patch, and also prior this patch, some NVMe disks which
> > support PCIe GEN3 with 8 GT/s speed are negotiated only at the lowest link
> > speed 2.5 GT/s, independently of SPEED_GEN value. After manually triggering
> > PCI_EXP_LNKCTL_RL bit (e.g. from userspace via setpci), these NVMe disks
> > change link speed to 5 GT/s when SPEED_GEN was configured to GEN2. This
> > issue first needs to be properly investigated. I will send a fix in the
> > future.
> > 
> > On the other hand, some other GEN2 PCIe cards with 5 GT/s speed are
> > autonomously by HW autonegotiated at full 5 GT/s speed without need of any
> > software interaction.
> > 
> > Armada 3700 Functional Specifications describes the following steps for
> > link training: set SPEED_GEN to GEN2, enable LINK_TRAINING_EN, poll until
> > link training is complete, trigger PCI_EXP_LNKCTL_RL, poll until signal
> > rate is 5 GT/s, poll until link training is complete, enable ASPM L0s.
> > 
> > The requirement for triggering PCI_EXP_LNKCTL_RL can be explained by the
> > need to achieve 5 GT/s speed (as changing link speed is done by throw to
> > recovery state entered by PCI_EXP_LNKCTL_RL) or maybe as a part of enabling
> > ASPM L0s (but in this case ASPM L0s should have been enabled prior
> > PCI_EXP_LNKCTL_RL).
> > 
> > It is unknown why the original pci-aardvark.c driver was triggering
> > PCI_EXP_LNKCTL_RL bit before waiting for the link to be up. This does not
> > align with neither PCIe base specifications nor with Armada 3700 Functional
> > Specification. (Note that in older versions of aardvark, this bit was
> > called incorrectly PCIE_CORE_LINK_TRAINING, so this may be the reason.)
> > 
> > It is also unknown why Armada 3700 Functional Specification says that it is
> > needed to trigger PCI_EXP_LNKCTL_RL for GEN2 mode, as according to PCIe
> > base specification 5 GT/s speed negotiation is supposed to be entirely
> > autonomous, even if initial speed is 2.5 GT/s.
> > 
> > [1] - https://lore.kernel.org/linux-pci/87h7l8axqp.fsf@toke.dk/
> > [2] - https://lore.kernel.org/linux-pci/20210326124326.21163-1-pali@kernel.org/
> > 
> > Signed-off-by: Pali Rohár <pali@kernel.org>
> > Reviewed-by: Marek Behún <kabel@kernel.org>
> > Signed-off-by: Marek Behún <kabel@kernel.org>
> > Cc: stable@vger.kernel.org # f4c7d053d7f7 ("PCI: aardvark: Wait for endpoint to be ready before training link")
> > Cc: stable@vger.kernel.org # 6964494582f5 ("PCI: aardvark: Train link immediately after enabling training")
> > Cc: stable@vger.kernel.org # 43fc679ced18 ("PCI: aardvark: Improve link training")
> > Cc: stable@vger.kernel.org # 5169a9851daa ("PCI: aardvark: Issue PERST via GPIO")
> > Cc: stable@vger.kernel.org # 96be36dbffac ("PCI: aardvark: Replace custom macros by standard linux/pci_regs.h macros")
> > Cc: stable@vger.kernel.org # d0c6a3475b03 ("PCI: aardvark: Move PCIe reset card code to advk_pcie_train_link()")
> > Cc: stable@vger.kernel.org # 1d1cd163d0de ("PCI: aardvark: Update comment about disabling link training")
> > ---
> >  drivers/pci/controller/pci-aardvark.c | 117 ++++++++------------------
> >  1 file changed, 34 insertions(+), 83 deletions(-)  
> 
> This is a very convoluted fix; it is well explained but the number
> of patches going into stable and the complexity of it make me ask
> how confident you are this won't trigger any regressions.
> 
> It is just a heads-up to make you think whether it is better to
> hold the stable tags till we are confident enough.
> 
> Please let me know.

Lorenzo,

you are probably right here. It would be better to have this in upstream
for some time and let people test it, and only afterward send it into
stable.

Let's remove the Fixes tag. We will send this into stable after it is a
little tested.

Marek

[PATCH v2 12/13] PCI: aardvark: Fix checking for link up via LTSSM state

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

Current implementation of advk_pcie_link_up() is wrong as it marks also
link disabled or hot reset states as link up.

Fix it by marking link up only to those states which are defined in PCIe
Base specification 3.0, Table 4-14: Link Status Mapped to the LTSSM.

To simplify implementation, Define macros for every LTSSM state which
aardvark hardware can return in CFG_REG register.

Fix also checking for link training according to the same Table 4-14.
Define a new function advk_pcie_link_training() for this purpose.

Fixes: 8c39d710363c ("PCI: aardvark: Add Aardvark PCI host controller driver")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: Remi Pommarel <repk@triplefau.lt>
Cc: stable@vger.kernel.org
---
 drivers/pci/controller/pci-aardvark.c | 76 ++++++++++++++++++++++++---
 1 file changed, 70 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 2c66cdbb8dd6..f831f7d197bd 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -165,8 +165,50 @@
 #define CFG_REG					(LMI_BASE_ADDR + 0x0)
 #define     LTSSM_SHIFT				24
 #define     LTSSM_MASK				0x3f
-#define     LTSSM_L0				0x10
 #define     RC_BAR_CONFIG			0x300
+
+/* LTSSM values in CFG_REG */
+enum {
+	LTSSM_DETECT_QUIET			= 0x0,
+	LTSSM_DETECT_ACTIVE			= 0x1,
+	LTSSM_POLLING_ACTIVE			= 0x2,
+	LTSSM_POLLING_COMPLIANCE		= 0x3,
+	LTSSM_POLLING_CONFIGURATION		= 0x4,
+	LTSSM_CONFIG_LINKWIDTH_START		= 0x5,
+	LTSSM_CONFIG_LINKWIDTH_ACCEPT		= 0x6,
+	LTSSM_CONFIG_LANENUM_ACCEPT		= 0x7,
+	LTSSM_CONFIG_LANENUM_WAIT		= 0x8,
+	LTSSM_CONFIG_COMPLETE			= 0x9,
+	LTSSM_CONFIG_IDLE			= 0xa,
+	LTSSM_RECOVERY_RCVR_LOCK		= 0xb,
+	LTSSM_RECOVERY_SPEED			= 0xc,
+	LTSSM_RECOVERY_RCVR_CFG			= 0xd,
+	LTSSM_RECOVERY_IDLE			= 0xe,
+	LTSSM_L0				= 0x10,
+	LTSSM_RX_L0S_ENTRY			= 0x11,
+	LTSSM_RX_L0S_IDLE			= 0x12,
+	LTSSM_RX_L0S_FTS			= 0x13,
+	LTSSM_TX_L0S_ENTRY			= 0x14,
+	LTSSM_TX_L0S_IDLE			= 0x15,
+	LTSSM_TX_L0S_FTS			= 0x16,
+	LTSSM_L1_ENTRY				= 0x17,
+	LTSSM_L1_IDLE				= 0x18,
+	LTSSM_L2_IDLE				= 0x19,
+	LTSSM_L2_TRANSMIT_WAKE			= 0x1a,
+	LTSSM_DISABLED				= 0x20,
+	LTSSM_LOOPBACK_ENTRY_MASTER		= 0x21,
+	LTSSM_LOOPBACK_ACTIVE_MASTER		= 0x22,
+	LTSSM_LOOPBACK_EXIT_MASTER		= 0x23,
+	LTSSM_LOOPBACK_ENTRY_SLAVE		= 0x24,
+	LTSSM_LOOPBACK_ACTIVE_SLAVE		= 0x25,
+	LTSSM_LOOPBACK_EXIT_SLAVE		= 0x26,
+	LTSSM_HOT_RESET				= 0x27,
+	LTSSM_RECOVERY_EQUALIZATION_PHASE0	= 0x28,
+	LTSSM_RECOVERY_EQUALIZATION_PHASE1	= 0x29,
+	LTSSM_RECOVERY_EQUALIZATION_PHASE2	= 0x2a,
+	LTSSM_RECOVERY_EQUALIZATION_PHASE3	= 0x2b,
+};
+
 #define VENDOR_ID_REG				(LMI_BASE_ADDR + 0x44)
 
 /* PCIe core controller registers */
@@ -258,13 +300,35 @@ static inline u32 advk_readl(struct advk_pcie *pcie, u64 reg)
 	return readl(pcie->base + reg);
 }
 
-static int advk_pcie_link_up(struct advk_pcie *pcie)
+static u8 advk_pcie_ltssm_state(struct advk_pcie *pcie)
 {
-	u32 val, ltssm_state;
+	u32 val;
+	u8 ltssm_state;
 
 	val = advk_readl(pcie, CFG_REG);
 	ltssm_state = (val >> LTSSM_SHIFT) & LTSSM_MASK;
-	return ltssm_state >= LTSSM_L0;
+	return ltssm_state;
+}
+
+static inline bool advk_pcie_link_up(struct advk_pcie *pcie)
+{
+	/* check if LTSSM is in normal operation - some L* state */
+	u8 ltssm_state = advk_pcie_ltssm_state(pcie);
+	return ltssm_state >= LTSSM_L0 && ltssm_state < LTSSM_DISABLED;
+}
+
+static inline bool advk_pcie_link_training(struct advk_pcie *pcie)
+{
+	/*
+	 * According to PCIe Base specification 3.0, Table 4-14: Link
+	 * Status Mapped to the LTSSM is Link Training mapped to LTSSM
+	 * Configuration and Recovery states.
+	 */
+	u8 ltssm_state = advk_pcie_ltssm_state(pcie);
+	return ((ltssm_state >= LTSSM_CONFIG_LINKWIDTH_START &&
+		 ltssm_state < LTSSM_L0) ||
+		(ltssm_state >= LTSSM_RECOVERY_EQUALIZATION_PHASE0 &&
+		 ltssm_state <= LTSSM_RECOVERY_EQUALIZATION_PHASE3));
 }
 
 static int advk_pcie_wait_for_link(struct advk_pcie *pcie)
@@ -287,7 +351,7 @@ static void advk_pcie_wait_for_retrain(struct advk_pcie *pcie)
 	size_t retries;
 
 	for (retries = 0; retries < RETRAIN_WAIT_MAX_RETRIES; ++retries) {
-		if (!advk_pcie_link_up(pcie))
+		if (advk_pcie_link_training(pcie))
 			break;
 		udelay(RETRAIN_WAIT_USLEEP_US);
 	}
@@ -706,7 +770,7 @@ advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 		/* u32 contains both PCI_EXP_LNKCTL and PCI_EXP_LNKSTA */
 		u32 val = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg) &
 			~(PCI_EXP_LNKSTA_LT << 16);
-		if (!advk_pcie_link_up(pcie))
+		if (advk_pcie_link_training(pcie))
 			val |= (PCI_EXP_LNKSTA_LT << 16);
 		*value = val;
 		return PCI_BRIDGE_EMUL_HANDLED;
-- 
2.32.0

[PATCH v2 13/13] PCI: aardvark: Fix reporting Data Link Layer Link Active

[Marek Behún]

From: Pali Rohár <pali@kernel.org>

Add support for reporting PCI_EXP_LNKSTA_DLLLA bit in Link Control register
on emulated bridge via current LTSSM state. Also correctly indicate DLLLA
capability via PCI_EXP_LNKCAP_DLLLARC bit in Link Control Capability
register.

Fixes: 8a3ebd8de328 ("PCI: aardvark: Implement emulated root PCI bridge config space")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: stable@vger.kernel.org
---
 drivers/pci/controller/pci-aardvark.c | 29 ++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index f831f7d197bd..10476c00b312 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -317,6 +317,20 @@ static inline bool advk_pcie_link_up(struct advk_pcie *pcie)
 	return ltssm_state >= LTSSM_L0 && ltssm_state < LTSSM_DISABLED;
 }
 
+static inline bool advk_pcie_link_active(struct advk_pcie *pcie)
+{
+	/*
+	 * According to PCIe Base specification 3.0, Table 4-14: Link
+	 * Status Mapped to the LTSSM, and 4.2.6.3.6 Configuration.Idle
+	 * is Link Up mapped to LTSSM Configuration.Idle, Recovery, L0,
+	 * L0s, L1 and L2 states. And according to 3.2.1. Data Link
+	 * Control and Management State Machine Rules is DL Up status
+	 * reported in DL Active state.
+	 */
+	u8 ltssm_state = advk_pcie_ltssm_state(pcie);
+	return ltssm_state >= LTSSM_CONFIG_IDLE && ltssm_state < LTSSM_DISABLED;
+}
+
 static inline bool advk_pcie_link_training(struct advk_pcie *pcie)
 {
 	/*
@@ -766,12 +780,26 @@ advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 		return PCI_BRIDGE_EMUL_HANDLED;
 	}
 
+	case PCI_EXP_LNKCAP: {
+		u32 val = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg);
+		/*
+		 * PCI_EXP_LNKCAP_DLLLARC bit is hardwired in aardvark HW to 0.
+		 * But support for PCI_EXP_LNKSTA_DLLLA is emulated via ltssm
+		 * state so explicitly enable PCI_EXP_LNKCAP_DLLLARC flag.
+		 */
+		val |= PCI_EXP_LNKCAP_DLLLARC;
+		*value = val;
+		return PCI_BRIDGE_EMUL_HANDLED;
+	}
+
 	case PCI_EXP_LNKCTL: {
 		/* u32 contains both PCI_EXP_LNKCTL and PCI_EXP_LNKSTA */
 		u32 val = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg) &
 			~(PCI_EXP_LNKSTA_LT << 16);
 		if (advk_pcie_link_training(pcie))
 			val |= (PCI_EXP_LNKSTA_LT << 16);
+		if (advk_pcie_link_active(pcie))
+			val |= (PCI_EXP_LNKSTA_DLLLA << 16);
 		*value = val;
 		return PCI_BRIDGE_EMUL_HANDLED;
 	}
@@ -779,7 +807,6 @@ advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 	case PCI_CAP_LIST_ID:
 	case PCI_EXP_DEVCAP:
 	case PCI_EXP_DEVCTL:
-	case PCI_EXP_LNKCAP:
 		*value = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg);
 		return PCI_BRIDGE_EMUL_HANDLED;
 	default:
-- 
2.32.0

Re: [PATCH v2 00/13] PCI: aardvark controller fixes

[Lorenzo Pieralisi]

On Tue, 5 Oct 2021 20:09:39 +0200, Marek Behún wrote:
> as requested I am sending v2 of this series.
> 
> Changes since v1:
> - updated commit message in patch 6 as suggested by Mark
> - updated patch 6 to also drop the early return
> - changed the LTSSM definitions to enum in patch 12
> - dropped the Fixes tags for those patches where it was inappropriate
> 
> [...]

I rewrote some logs, dropped some stable tags. This series raised
a couple of interesting questions that may be relevant for PCI core
as well, it'd be great if those won't be lost but I feel it is time
to merge this series to help Marek/Pali cut the patch delta and
give this code wider testing.

I have applied it to pci/aardvark, please _do_ have a look and
report back any issue with it.

[01/13] PCI: Add PCI_EXP_DEVCTL_PAYLOAD_* macros
        https://git.kernel.org/lpieralisi/pci/c/460275f124
[02/13] PCI: aardvark: Fix PCIe Max Payload Size setting
        https://git.kernel.org/lpieralisi/pci/c/a4e17d65da
[03/13] PCI: aardvark: Don't spam about PIO Response Status
        https://git.kernel.org/lpieralisi/pci/c/464de7e7ff
[04/13] PCI: aardvark: Fix preserving PCI_EXP_RTCTL_CRSSVE flag on emulated bridge
        https://git.kernel.org/lpieralisi/pci/c/d419052bc6
[05/13] PCI: aardvark: Fix configuring Reference clock
        https://git.kernel.org/lpieralisi/pci/c/46ef6090db
[06/13] PCI: aardvark: Do not clear status bits of masked interrupts
        https://git.kernel.org/lpieralisi/pci/c/a7ca6d7fa3
[07/13] PCI: aardvark: Do not unmask unused interrupts
        https://git.kernel.org/lpieralisi/pci/c/1fb95d7d3c
[08/13] PCI: aardvark: Deduplicate code in advk_pcie_rd_conf()
        https://git.kernel.org/lpieralisi/pci/c/67cb2a4c93
[09/13] PCI: aardvark: Implement re-issuing config requests on CRS response
        https://git.kernel.org/lpieralisi/pci/c/223dec14a0
[10/13] PCI: aardvark: Simplify initialization of rootcap on virtual bridge
        https://git.kernel.org/lpieralisi/pci/c/454c53271f
[11/13] PCI: aardvark: Fix link training
        https://git.kernel.org/lpieralisi/pci/c/f76b36d40b
[12/13] PCI: aardvark: Fix checking for link up via LTSSM state
        https://git.kernel.org/lpieralisi/pci/c/661c399a65
[13/13] PCI: aardvark: Fix reporting Data Link Layer Link Active
        https://git.kernel.org/lpieralisi/pci/c/2b650b7ff2

Thanks,
Lorenzo

Re: [PATCH v2 00/13] PCI: aardvark controller fixes

[Marek Behún]

On Thu,  7 Oct 2021 14:38:25 +0100
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote:

> On Tue, 5 Oct 2021 20:09:39 +0200, Marek Behún wrote:
> > as requested I am sending v2 of this series.
> > 
> > Changes since v1:
> > - updated commit message in patch 6 as suggested by Mark
> > - updated patch 6 to also drop the early return
> > - changed the LTSSM definitions to enum in patch 12
> > - dropped the Fixes tags for those patches where it was inappropriate
> > 
> > [...]  
> 
> I rewrote some logs, dropped some stable tags. This series raised
> a couple of interesting questions that may be relevant for PCI core
> as well, it'd be great if those won't be lost but I feel it is time
> to merge this series to help Marek/Pali cut the patch delta and
> give this code wider testing.
> 
> I have applied it to pci/aardvark, please _do_ have a look and
> report back any issue with it.

I checked all the commit messages in pci/aardvark.

I also compiled this branch and tested it on my Mox with ath10k card
and it works correctly, no regressions.

Marek