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SubjectRe: [PATCH v8 4/4] USB: pci-quirks: Add Raspberry Pi 4 quirk
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On Tue, 2020-05-05 at 18:13 +0200, Nicolas Saenz Julienne wrote:
> On the Raspberry Pi 4, after a PCI reset, VL805's firmware may either be
> loaded directly from an EEPROM or, if not present, by the SoC's
> VideoCore. Inform VideoCore that VL805 was just reset.
>
> Also, as this creates a dependency between USB_PCI and VideoCore's
> firmware interface, and since USB_PCI can't be set as a module neither
> this can. Reflect that on the firmware interface Kconfg.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---

It was pointed out to me on the u-boot mailing lists that all this could be
implemented trough a reset controller. In other words have xhci get the reset
controller trough device-tree, assert it, ultamately causing the firmware
routine to be run.

As much as it pains me to go over stuff that's already 'fixed', it seems to me
it's a better solution. On one hand we get over the device-tree dependency mess
(see patch #3), and on the other we transform a pci-quirk into something less
hacky.

That said, before getting my hands dirty, I was wondering if there is any
obvious reasons why I shouldn't do this, note that:

- We're talking here of a PCIe XCHI device, maybe there's an issue integrating
it with DT, given the fact that, as of today, it's not really represented
there.

- There is no reset controller support in xhci-pci, maybe there are good
reasons why. For instance, it's not something that's reflected in any way in
the spec.

Regards,
Nicolas

>
> Changes since v5:
> - Fix Kconfig issue with allmodconfig
>
> Changes since v4:
> - Do not split up error message
>
> Changes since v3:
> - Add more complete error message
>
> Changes since v1:
> - Make RASPBERRYPI_FIRMWARE dependent on this quirk to make sure it
> gets compiled when needed.
>
> drivers/firmware/Kconfig | 3 ++-
> drivers/usb/host/pci-quirks.c | 16 ++++++++++++++++
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index 8007d4aa76dc..b42140cff8ac 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -178,8 +178,9 @@ config ISCSI_IBFT
> Otherwise, say N.
>
> config RASPBERRYPI_FIRMWARE
> - tristate "Raspberry Pi Firmware Driver"
> + bool "Raspberry Pi Firmware Driver"
> depends on BCM2835_MBOX
> + default USB_PCI
> help
> This option enables support for communicating with the firmware on the
> Raspberry Pi.
> diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
> index 92150ecdb036..0b949acfa258 100644
> --- a/drivers/usb/host/pci-quirks.c
> +++ b/drivers/usb/host/pci-quirks.c
> @@ -16,6 +16,9 @@
> #include <linux/export.h>
> #include <linux/acpi.h>
> #include <linux/dmi.h>
> +
> +#include <soc/bcm2835/raspberrypi-firmware.h>
> +
> #include "pci-quirks.h"
> #include "xhci-ext-caps.h"
>
> @@ -1243,11 +1246,24 @@ static void quirk_usb_handoff_xhci(struct pci_dev
> *pdev)
>
> static void quirk_usb_early_handoff(struct pci_dev *pdev)
> {
> + int ret;
> +
> /* Skip Netlogic mips SoC's internal PCI USB controller.
> * This device does not need/support EHCI/OHCI handoff
> */
> if (pdev->vendor == 0x184e) /* vendor Netlogic */
> return;
> +
> + if (pdev->vendor == PCI_VENDOR_ID_VIA && pdev->device == 0x3483) {
> + ret = rpi_firmware_init_vl805(pdev);
> + if (ret) {
> + /* Firmware might be outdated, or something failed */
> + dev_warn(&pdev->dev,
> + "Failed to load VL805's firmware: %d. Will
> continue to attempt to work, but bad things might happen. You should fix
> this...\n",
> + ret);
> + }
> + }
> +
> if (pdev->class != PCI_CLASS_SERIAL_USB_UHCI &&
> pdev->class != PCI_CLASS_SERIAL_USB_OHCI &&
> pdev->class != PCI_CLASS_SERIAL_USB_EHCI &&

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