Re: [PATCH] ata: libata-eh: Fix link state check for IDE/PATA ports

[Niklas Cassel <cassel@kernel.org>]

On Wed, Aug 13, 2025 at 06:27:07PM +0900, Damien Le Moal wrote:
> Commit 4371fe1ba400 ("ata: libata-eh: Avoid unnecessary resets when
> revalidating devices") replaced the call to ata_phys_link_offline() in
> ata_eh_revalidate_and_attach() with the new function
> ata_eh_link_established() which relaxes the checks on a device link
> state to account for low power mode transitions. However, this changed

s/changed/change/

> assumed that the device port has a valid scr_read method to obstain the

s/obstain/obtain/

> SSTATUS register for the port. This is not always the case, especially
> with older IDE/PATA adapters (e.g. as emulated with qemu). For such

s/emulated with qemu/PATA emulated with QEMU/

(QEMU also support AHCI emulation)

> adapter, ata_eh_link_established() will always return false, causing
> ata_eh_revalidate_and_attach() to go into its error path and ultimately
> to the device being disabled.
> 
> Avoid this by restoring the previous behavior, which is to assume that
> the link is online if reading the port SSTATUS register fails.
> 
> Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> Fixes: 4371fe1ba400 ("ata: libata-eh: Avoid unnecessary resets when revalidating devices")
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>

Reviewed-by: Niklas Cassel <cassel@kernel.org>