* [RESEND PATCH] PCI: cadence: Fix Gen2 Link Retraining process
@ 2023-01-02 7:56 Siddharth Vadapalli
2023-01-10 10:33 ` Siddharth Vadapalli
2023-01-25 14:15 ` Vignesh Raghavendra
0 siblings, 2 replies; 3+ messages in thread
From: Siddharth Vadapalli @ 2023-01-02 7:56 UTC (permalink / raw)
To: tjoseph, lpieralisi, robh, kw, bhelgaas, nadeem
Cc: linux-pci, linux-kernel, linux-arm-kernel, vigneshr, srk, nm,
s-vadapalli
The Link Retraining process is initiated to account for the Gen2 defect in
the Cadence PCIe controller in J721E SoC. The errata corresponding to this
is i2085, documented at:
https://www.ti.com/lit/er/sprz455c/sprz455c.pdf
The existing workaround implemented for the errata waits for the Data Link
initialization to complete and assumes that the link retraining process
at the Physical Layer has completed. However, it is possible that the
Physical Layer training might be ongoing as indicated by the
PCI_EXP_LNKSTA_LT bit in the PCI_EXP_LNKSTA register.
Fix the existing workaround, to ensure that the Physical Layer training
has also completed, in addition to the Data Link initialization.
Fixes: 4740b969aaf5 ("PCI: cadence: Retrain Link to work around Gen2 training defect")
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
---
.../controller/cadence/pcie-cadence-host.c | 27 +++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index 940c7dd701d6..5b14f7ee3c79 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -12,6 +12,8 @@
#include "pcie-cadence.h"
+#define LINK_RETRAIN_TIMEOUT HZ
+
static u64 bar_max_size[] = {
[RP_BAR0] = _ULL(128 * SZ_2G),
[RP_BAR1] = SZ_2G,
@@ -77,6 +79,27 @@ static struct pci_ops cdns_pcie_host_ops = {
.write = pci_generic_config_write,
};
+static int cdns_pcie_host_training_complete(struct cdns_pcie *pcie)
+{
+ u32 pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
+ unsigned long end_jiffies;
+ u16 lnk_stat;
+
+ /* Wait for link training to complete. Exit after timeout. */
+ end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT;
+ do {
+ lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off + PCI_EXP_LNKSTA);
+ if (!(lnk_stat & PCI_EXP_LNKSTA_LT))
+ break;
+ usleep_range(0, 1000);
+ } while (time_before(jiffies, end_jiffies));
+
+ if (!(lnk_stat & PCI_EXP_LNKSTA_LT))
+ return 0;
+
+ return -ETIMEDOUT;
+}
+
static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie)
{
struct device *dev = pcie->dev;
@@ -118,6 +141,10 @@ static int cdns_pcie_retrain(struct cdns_pcie *pcie)
cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL,
lnk_ctl);
+ ret = cdns_pcie_host_training_complete(pcie);
+ if (ret)
+ return ret;
+
ret = cdns_pcie_host_wait_for_link(pcie);
}
return ret;
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RESEND PATCH] PCI: cadence: Fix Gen2 Link Retraining process
2023-01-02 7:56 [RESEND PATCH] PCI: cadence: Fix Gen2 Link Retraining process Siddharth Vadapalli
@ 2023-01-10 10:33 ` Siddharth Vadapalli
2023-01-25 14:15 ` Vignesh Raghavendra
1 sibling, 0 replies; 3+ messages in thread
From: Siddharth Vadapalli @ 2023-01-10 10:33 UTC (permalink / raw)
To: tjoseph, lpieralisi, robh, kw, bhelgaas, nadeem
Cc: linux-pci, linux-kernel, linux-arm-kernel, vigneshr, srk, nm,
s-vadapalli
Hello All,
Can this patch please be merged in case of no feedback or issues?
Regards,
Siddharth.
On 02/01/23 13:26, Siddharth Vadapalli wrote:
> The Link Retraining process is initiated to account for the Gen2 defect in
> the Cadence PCIe controller in J721E SoC. The errata corresponding to this
> is i2085, documented at:
> https://www.ti.com/lit/er/sprz455c/sprz455c.pdf
>
> The existing workaround implemented for the errata waits for the Data Link
> initialization to complete and assumes that the link retraining process
> at the Physical Layer has completed. However, it is possible that the
> Physical Layer training might be ongoing as indicated by the
> PCI_EXP_LNKSTA_LT bit in the PCI_EXP_LNKSTA register.
>
> Fix the existing workaround, to ensure that the Physical Layer training
> has also completed, in addition to the Data Link initialization.
>
> Fixes: 4740b969aaf5 ("PCI: cadence: Retrain Link to work around Gen2 training defect")
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
> ---
> .../controller/cadence/pcie-cadence-host.c | 27 +++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index 940c7dd701d6..5b14f7ee3c79 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -12,6 +12,8 @@
>
> #include "pcie-cadence.h"
>
> +#define LINK_RETRAIN_TIMEOUT HZ
> +
> static u64 bar_max_size[] = {
> [RP_BAR0] = _ULL(128 * SZ_2G),
> [RP_BAR1] = SZ_2G,
> @@ -77,6 +79,27 @@ static struct pci_ops cdns_pcie_host_ops = {
> .write = pci_generic_config_write,
> };
>
> +static int cdns_pcie_host_training_complete(struct cdns_pcie *pcie)
> +{
> + u32 pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
> + unsigned long end_jiffies;
> + u16 lnk_stat;
> +
> + /* Wait for link training to complete. Exit after timeout. */
> + end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT;
> + do {
> + lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off + PCI_EXP_LNKSTA);
> + if (!(lnk_stat & PCI_EXP_LNKSTA_LT))
> + break;
> + usleep_range(0, 1000);
> + } while (time_before(jiffies, end_jiffies));
> +
> + if (!(lnk_stat & PCI_EXP_LNKSTA_LT))
> + return 0;
> +
> + return -ETIMEDOUT;
> +}
> +
> static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie)
> {
> struct device *dev = pcie->dev;
> @@ -118,6 +141,10 @@ static int cdns_pcie_retrain(struct cdns_pcie *pcie)
> cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL,
> lnk_ctl);
>
> + ret = cdns_pcie_host_training_complete(pcie);
> + if (ret)
> + return ret;
> +
> ret = cdns_pcie_host_wait_for_link(pcie);
> }
> return ret;
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RESEND PATCH] PCI: cadence: Fix Gen2 Link Retraining process
2023-01-02 7:56 [RESEND PATCH] PCI: cadence: Fix Gen2 Link Retraining process Siddharth Vadapalli
2023-01-10 10:33 ` Siddharth Vadapalli
@ 2023-01-25 14:15 ` Vignesh Raghavendra
1 sibling, 0 replies; 3+ messages in thread
From: Vignesh Raghavendra @ 2023-01-25 14:15 UTC (permalink / raw)
To: Siddharth Vadapalli, tjoseph, lpieralisi, robh, kw, bhelgaas, nadeem
Cc: linux-pci, linux-kernel, linux-arm-kernel, srk, nm
On 02/01/23 1:26 pm, Siddharth Vadapalli wrote:
> The Link Retraining process is initiated to account for the Gen2 defect in
> the Cadence PCIe controller in J721E SoC. The errata corresponding to this
> is i2085, documented at:
> https://www.ti.com/lit/er/sprz455c/sprz455c.pdf
>
> The existing workaround implemented for the errata waits for the Data Link
> initialization to complete and assumes that the link retraining process
> at the Physical Layer has completed. However, it is possible that the
> Physical Layer training might be ongoing as indicated by the
> PCI_EXP_LNKSTA_LT bit in the PCI_EXP_LNKSTA register.
>
> Fix the existing workaround, to ensure that the Physical Layer training
> has also completed, in addition to the Data Link initialization.
>
> Fixes: 4740b969aaf5 ("PCI: cadence: Retrain Link to work around Gen2 training defect")
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
> ---
> .../controller/cadence/pcie-cadence-host.c | 27 +++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index 940c7dd701d6..5b14f7ee3c79 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -12,6 +12,8 @@
>
> #include "pcie-cadence.h"
>
> +#define LINK_RETRAIN_TIMEOUT HZ
> +
> static u64 bar_max_size[] = {
> [RP_BAR0] = _ULL(128 * SZ_2G),
> [RP_BAR1] = SZ_2G,
> @@ -77,6 +79,27 @@ static struct pci_ops cdns_pcie_host_ops = {
> .write = pci_generic_config_write,
> };
>
> +static int cdns_pcie_host_training_complete(struct cdns_pcie *pcie)
> +{
> + u32 pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
> + unsigned long end_jiffies;
> + u16 lnk_stat;
> +
> + /* Wait for link training to complete. Exit after timeout. */
> + end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT;
> + do {
> + lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off + PCI_EXP_LNKSTA);
> + if (!(lnk_stat & PCI_EXP_LNKSTA_LT))
> + break;
> + usleep_range(0, 1000);
> + } while (time_before(jiffies, end_jiffies));
> +
> + if (!(lnk_stat & PCI_EXP_LNKSTA_LT))
> + return 0;
> +
> + return -ETIMEDOUT;
> +}
> +
> static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie)
> {
> struct device *dev = pcie->dev;
> @@ -118,6 +141,10 @@ static int cdns_pcie_retrain(struct cdns_pcie *pcie)
> cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL,
> lnk_ctl);
>
> + ret = cdns_pcie_host_training_complete(pcie);
> + if (ret)
> + return ret;
> +
> ret = cdns_pcie_host_wait_for_link(pcie);
> }
> return ret;
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Regards
Vignesh
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-01-25 14:16 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-01-02 7:56 [RESEND PATCH] PCI: cadence: Fix Gen2 Link Retraining process Siddharth Vadapalli
2023-01-10 10:33 ` Siddharth Vadapalli
2023-01-25 14:15 ` Vignesh Raghavendra
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).