Re: [PATCH] ahci: Improve error handling

[Daniel Kiper]

On Fri, Jan 19, 2018 at 02:13:29PM +0100, Stefan Fritsch wrote:
> From: Stefan Fritsch <address@hidden>
>
> Check the error bits in the interrupt status register. According to the
> AHCI 1.2 spec, "Interrupt sources that are disabled (?0?) are still
> reflected in the status registers.", so this should work even though
> grub uses polling
>
> This fixes the following problem on a Fujitsu E744 laptop:
>
> Sometimes there is a very long delay (up to several minutes) when
> booting from hard disk. It seems accessing the DVD drive (which has no
> disk inserted) sometimes fails with some errors, which leads to each
> access being stalled until the 20s timeout triggers. This seems to
> happen when grub is trying to read filesystem/partition data.
>
> The problem is that the command_issue bit that is checked in the loop is
> only reset if the "HBA receives a FIS which clears the BSY, DRQ, and ERR
> bits for the command", but the ERR bit is never cleared. Therefore
> command_issue is never reset and grub waits for the timeout.
>
> The relevant bit in our case is the Task File Error Status (TFES), which
> is equivalent to the ERR bit 0 in tfd. But this patch also checks
> the other error bits except for the "Interface non-fatal error status"
> bit.
>
> Signed-off-by: Stefan Fritsch <address@hidden>

Reviewed-by: Daniel Kiper <address@hidden>

If there are no objections I will apply this by the end of this week.

Daniel