From: Robin Murphy <robin.murphy@arm.com> To: Jeremy Linton <jeremy.linton@arm.com>, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>, andrew.murray@arm.com, maz@kernel.org, linux-kernel@vger.kernel.org, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Eric Anholt <eric@anholt.net>, Stefan Wahren <wahrenst@gmx.net>, Florian Fainelli <f.fainelli@gmail.com>, bcm-kernel-feedback-list@broadcom.com Cc: mbrugger@suse.com, linux-pci@vger.kernel.org, phil@raspberrypi.org, linux-rpi-kernel@lists.infradead.org, james.quinlan@broadcom.com, Bjorn Helgaas <bhelgaas@google.com>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 4/7] PCI: brcmstb: add Broadcom STB PCIe host controller driver Date: Tue, 3 Dec 2019 16:48:37 +0000 [thread overview] Message-ID: <dda72ec5-3e05-a423-bfce-da34addc922c@arm.com> (raw) In-Reply-To: <ddab6abd-68fb-543d-bb8e-057d92ac15ed@arm.com> On 03/12/2019 4:31 pm, Jeremy Linton wrote: > Hi, > > On 11/26/19 3:19 AM, Nicolas Saenz Julienne wrote: >> From: Jim Quinlan <james.quinlan@broadcom.com> >> >> This adds a basic driver for Broadcom's STB PCIe controller, for now >> aimed at Raspberry Pi 4's SoC, bcm2711. >> >> Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com> >> Co-developed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> >> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> >> >> --- >> >> Changes since v2: >> - Correct rc_bar2_offset sign >> - Invert IRQ clear and masking in setup code >> - Use bitfield.h, redo all register ops while keeping the register >> names intact >> - Remove all SHIFT register definitions >> - Get rid of all _RB writes >> - Get rid of of_data >> - Don't iterate over inexisting dma-ranges >> - Add comment regarding dma-ranges validation >> - Small cosmetic cleanups >> - Fix license mismatch >> - Set driver Kconfig tristate >> - Didn't add any comment about the controller not being I/O coherent >> for now as I wait for Jeremy's reply > > I guess its fine.. In answer to the original query. It seems that this > PCIe bridge requires explicit cache operations for DMA from PCIe > endpoints. This wasn't obvious to me at first reading because I was > assuming the custom DMA ops were strictly to deal with the stated DMA > limits. FWIW, although it might seem anathema to server folks, non-coherent PCI is the overwhelming norm in embedded SoCs. Either way, provided the presence or absence of coherency is correctly described via the DT "dma-coherent" or ACPI _CCA property, then it's transparently handled by the DMA API for the endpoint drivers and irrelevant to the host bridge itself - after all, in principle the exact same root complex IP could be integrated both coherently and non-coherently in different SoCs. Robin. > So if you end up respinning, it still might be worthy mentioning > somewhere that this is a non-coherent PCIe implementation. I still hold > much of my original reservations about pieces of this driver. > Particularly, how it might look if someone wanted to boot the RPi using > ACPI on linux. But, I was shown a clever bit of AML recently, which > solves those problems for the RPi and the attached XHCI. > > So, given how much time I've looked at the root port configuration/etc > sections of this driver and I've not found a serious bug: > > Reviewed-by: Jeremy Linton <jeremy.linton@arm.com> > >> >> Changes since v1: >> - Fix Kconfig >> - Remove pci domain check >> - Remove all MSI related code >> - Remove supend/resume code >> - Simplify link state wait routine >> - Prefix all functions >> - Use of_device_get_match_data() >> - Use devm_clk_get_optional() >> - Get rid of irq variable >> - Use STB all over the driver >> - Simplify map_bus() function >> - Fix license mismatch >> - Remove unused register definitions >> - Small cleanups, spell errors >> >> This is based on Jim's original submission[1] but adapted and tailored >> specifically to bcm2711's needs (that's the Raspberry Pi 4). Support for >> the rest of the brcmstb family will soon follow once we get support for >> multiple dma-ranges in dma/direct. >> >> [1] https://patchwork.kernel.org/patch/10605959/ >> >> drivers/pci/controller/Kconfig | 8 + >> drivers/pci/controller/Makefile | 1 + >> drivers/pci/controller/pcie-brcmstb.c | 753 ++++++++++++++++++++++++++ >> 3 files changed, 762 insertions(+) >> create mode 100644 drivers/pci/controller/pcie-brcmstb.c >> > > Thanks, > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com> To: Jeremy Linton <jeremy.linton@arm.com>, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>, andrew.murray@arm.com, maz@kernel.org, linux-kernel@vger.kernel.org, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Eric Anholt <eric@anholt.net>, Stefan Wahren <wahrenst@gmx.net>, Florian Fainelli <f.fainelli@gmail.com>, bcm-kernel-feedback-list@broadcom.com Cc: mbrugger@suse.com, linux-pci@vger.kernel.org, phil@raspberrypi.org, linux-rpi-kernel@lists.infradead.org, james.quinlan@broadcom.com, Bjorn Helgaas <bhelgaas@google.com>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 4/7] PCI: brcmstb: add Broadcom STB PCIe host controller driver Date: Tue, 3 Dec 2019 16:48:37 +0000 [thread overview] Message-ID: <dda72ec5-3e05-a423-bfce-da34addc922c@arm.com> (raw) In-Reply-To: <ddab6abd-68fb-543d-bb8e-057d92ac15ed@arm.com> On 03/12/2019 4:31 pm, Jeremy Linton wrote: > Hi, > > On 11/26/19 3:19 AM, Nicolas Saenz Julienne wrote: >> From: Jim Quinlan <james.quinlan@broadcom.com> >> >> This adds a basic driver for Broadcom's STB PCIe controller, for now >> aimed at Raspberry Pi 4's SoC, bcm2711. >> >> Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com> >> Co-developed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> >> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> >> >> --- >> >> Changes since v2: >> - Correct rc_bar2_offset sign >> - Invert IRQ clear and masking in setup code >> - Use bitfield.h, redo all register ops while keeping the register >> names intact >> - Remove all SHIFT register definitions >> - Get rid of all _RB writes >> - Get rid of of_data >> - Don't iterate over inexisting dma-ranges >> - Add comment regarding dma-ranges validation >> - Small cosmetic cleanups >> - Fix license mismatch >> - Set driver Kconfig tristate >> - Didn't add any comment about the controller not being I/O coherent >> for now as I wait for Jeremy's reply > > I guess its fine.. In answer to the original query. It seems that this > PCIe bridge requires explicit cache operations for DMA from PCIe > endpoints. This wasn't obvious to me at first reading because I was > assuming the custom DMA ops were strictly to deal with the stated DMA > limits. FWIW, although it might seem anathema to server folks, non-coherent PCI is the overwhelming norm in embedded SoCs. Either way, provided the presence or absence of coherency is correctly described via the DT "dma-coherent" or ACPI _CCA property, then it's transparently handled by the DMA API for the endpoint drivers and irrelevant to the host bridge itself - after all, in principle the exact same root complex IP could be integrated both coherently and non-coherently in different SoCs. Robin. > So if you end up respinning, it still might be worthy mentioning > somewhere that this is a non-coherent PCIe implementation. I still hold > much of my original reservations about pieces of this driver. > Particularly, how it might look if someone wanted to boot the RPi using > ACPI on linux. But, I was shown a clever bit of AML recently, which > solves those problems for the RPi and the attached XHCI. > > So, given how much time I've looked at the root port configuration/etc > sections of this driver and I've not found a serious bug: > > Reviewed-by: Jeremy Linton <jeremy.linton@arm.com> > >> >> Changes since v1: >> - Fix Kconfig >> - Remove pci domain check >> - Remove all MSI related code >> - Remove supend/resume code >> - Simplify link state wait routine >> - Prefix all functions >> - Use of_device_get_match_data() >> - Use devm_clk_get_optional() >> - Get rid of irq variable >> - Use STB all over the driver >> - Simplify map_bus() function >> - Fix license mismatch >> - Remove unused register definitions >> - Small cleanups, spell errors >> >> This is based on Jim's original submission[1] but adapted and tailored >> specifically to bcm2711's needs (that's the Raspberry Pi 4). Support for >> the rest of the brcmstb family will soon follow once we get support for >> multiple dma-ranges in dma/direct. >> >> [1] https://patchwork.kernel.org/patch/10605959/ >> >> drivers/pci/controller/Kconfig | 8 + >> drivers/pci/controller/Makefile | 1 + >> drivers/pci/controller/pcie-brcmstb.c | 753 ++++++++++++++++++++++++++ >> 3 files changed, 762 insertions(+) >> create mode 100644 drivers/pci/controller/pcie-brcmstb.c >> > > Thanks, > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-12-03 16:48 UTC|newest] Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-11-26 9:19 [PATCH v3 0/7] Raspberry Pi 4 PCIe support Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-11-26 9:19 ` [PATCH v3 1/7] linux/log2.h: Add roundup/rounddown_pow_two64() family of functions Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-11-26 12:51 ` Leon Romanovsky 2019-11-26 12:51 ` Leon Romanovsky 2019-11-26 12:51 ` Leon Romanovsky 2019-11-26 12:51 ` Leon Romanovsky 2019-11-27 18:06 ` Robin Murphy 2019-11-27 18:06 ` Robin Murphy 2019-11-27 18:06 ` Robin Murphy 2019-11-27 18:06 ` Robin Murphy 2019-11-27 18:24 ` Nicolas Saenz Julienne 2019-11-27 18:24 ` Nicolas Saenz Julienne 2019-11-27 18:24 ` Nicolas Saenz Julienne 2019-11-27 18:24 ` Nicolas Saenz Julienne 2019-11-27 19:06 ` Robin Murphy 2019-11-27 19:06 ` Robin Murphy 2019-11-27 19:06 ` Robin Murphy 2019-11-27 19:06 ` Robin Murphy 2019-11-27 19:12 ` Leon Romanovsky 2019-11-27 19:12 ` Leon Romanovsky 2019-11-27 19:12 ` Leon Romanovsky 2019-11-27 19:12 ` Leon Romanovsky 2019-11-27 19:16 ` Nicolas Saenz Julienne 2019-11-27 19:16 ` Nicolas Saenz Julienne 2019-11-27 19:16 ` Nicolas Saenz Julienne 2019-11-27 19:16 ` Nicolas Saenz Julienne 2019-11-27 17:36 ` Nicolas Saenz Julienne 2019-11-27 17:36 ` Nicolas Saenz Julienne 2019-11-27 17:36 ` Nicolas Saenz Julienne 2019-11-26 9:19 ` [PATCH v3 2/7] dt-bindings: PCI: Add bindings for brcmstb's PCIe device Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-12-02 16:39 ` Rob Herring 2019-12-02 16:39 ` Rob Herring 2019-11-26 9:19 ` [PATCH v3 3/7] ARM: dts: bcm2711: Enable PCIe controller Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-11-26 9:37 ` Phil Elwell 2019-11-26 9:37 ` Phil Elwell 2019-11-26 9:43 ` Nicolas Saenz Julienne 2019-11-26 9:43 ` Nicolas Saenz Julienne 2019-11-26 9:19 ` [PATCH v3 4/7] PCI: brcmstb: add Broadcom STB PCIe host controller driver Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-12-02 15:01 ` Andrew Murray 2019-12-02 15:01 ` Andrew Murray 2019-12-02 15:49 ` Jim Quinlan 2019-12-02 15:49 ` Jim Quinlan 2019-12-03 16:31 ` Jeremy Linton 2019-12-03 16:31 ` Jeremy Linton 2019-12-03 16:48 ` Robin Murphy [this message] 2019-12-03 16:48 ` Robin Murphy 2019-12-03 17:23 ` Nicolas Saenz Julienne 2019-12-03 17:23 ` Nicolas Saenz Julienne 2019-11-26 9:19 ` [PATCH v3 5/7] PCI: brcmstb: add MSI capability Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-11-29 15:46 ` Andrew Murray 2019-11-29 15:46 ` Andrew Murray 2019-12-02 9:59 ` Nicolas Saenz Julienne 2019-12-02 9:59 ` Nicolas Saenz Julienne 2019-12-02 12:20 ` Andrew Murray 2019-12-02 12:20 ` Andrew Murray 2019-12-02 12:22 ` Nicolas Saenz Julienne 2019-12-02 12:22 ` Nicolas Saenz Julienne 2019-11-26 9:19 ` [PATCH v3 6/7] MAINTAINERS: Add brcmstb PCIe controller Nicolas Saenz Julienne 2019-11-26 9:19 ` [PATCH v3 7/7] arm64: defconfig: Enable Broadcom's STB " Nicolas Saenz Julienne 2019-11-26 9:19 ` Nicolas Saenz Julienne 2019-11-26 21:50 ` [PATCH v3 0/7] Raspberry Pi 4 PCIe support Bjorn Helgaas 2019-11-26 21:50 ` Bjorn Helgaas 2019-11-26 21:50 ` Bjorn Helgaas 2019-11-27 17:28 ` Nicolas Saenz Julienne 2019-11-27 17:28 ` Nicolas Saenz Julienne 2019-11-27 17:28 ` Nicolas Saenz Julienne
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