Re: [PATCH] tty: rp2: Fix reset with non forgiving PCIe host bridges

[Greg Kroah-Hartman]

On Fri, Sep 06, 2024 at 03:54:33PM -0700, Florian Fainelli wrote:
> The write to RP2_GLOBAL_CMD followed by an immediate read of
> RP2_GLOBAL_CMD in rp2_reset_asic() is intented to flush out the write,
> however by then the device is already in reset and cannot respond to a
> memory cycle access.
> 
> On platforms such as the Raspberry Pi 4 and others using the
> pcie-brcmstb.c driver, any memory access to a device that cannot respond
> is met with a fatal system error, rather than being substituted with all
> 1s as is usually the case on PC platforms.
> 
> Swapping the delay and the read ensures that the device has finished
> resetting before we attempt to read from it.
> 
> Fixes: 7d9f49afa451 ("serial: rp2: New driver for Comtrol RocketPort 2 cards")
> Suggested-by: Jim Quinlan <james.quinlan@xxxxxxxxxxxx>
> Signed-off-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
> ---
>  drivers/tty/serial/rp2.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Hi,

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