[PATCH v2] PCI: brcmstb: Restore initial fundamental reset

[Stefan Wahren]

Hi,

Am 12.11.20 um 18:27 schrieb Phil Elwell:
> Commit 04356ac30771 ("PCI: brcmstb: Add bcm7278 PERST# support")
> replaced a single reset function with a pointer to one of two
> implementations, but also removed the call asserting the reset
> at the start of brcm_pcie_setup. Doing so breaks Raspberry Pis with
> VL805 XHCI controllers lacking dedicated SPI EEPROMs, which have been
> used for USB booting but then need to be reset so that the kernel
> can reconfigure them. The lack of a reset causes the firmware's loading
> of the EEPROM image to RAM to fail, breaking USB for the kernel.
>
> Fixes: commit 04356ac30771 ("PCI: brcmstb: Add bcm7278 PERST# support")
>
> Signed-off-by: Phil Elwell <phil at raspberrypi.com>
> Acked-by: Nicolas Saenz Julienne <nsaenzjulienne at suse.de>
> ---
> Changes in v2:
>   - Exclude BCM7278 from the initial reset
>   - Ack from Nicolas
> ---
>  drivers/pci/controller/pcie-brcmstb.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index bea86899bd5d..83aa85bfe8e3 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -869,6 +869,11 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
>  
>  	/* Reset the bridge */
>  	pcie->bridge_sw_init_set(pcie, 1);
> +
> +	/* Assert the fundemental reset, except on BCM7278 */
> +	if (pcie->type != BCM7278)
> +		pcie->perst_set(pcie, 1);

since only the Raspberry Pi 4 requires the reset i had changed the logic
to pcie->type == BCM2711. But this isn't totally clean, since we need
this quirk only for the Raspberry Pi 4 and not for CM4 (which also has a
BCM2711 SoC). So maybe we should introduce BCM2711_RPI4 to be on the
safe side. Sorry for the bikeshedding.

Stefan

> +
>  	usleep_range(100, 200);
>  
>  	/* Take the bridge out of reset */