Tejun Heo wrote:
ata_set_mode() used to disable whole port on failure. This patch adds
@disable_on_err which makes ata_set_mode() disable failing devices
when non-zero, and simply return when zero. Due to the port-wide
characteristic of ATA xfer mode configuration, ata_mode_set() is the
final place to determine device offlining; thus, the @disable_on_err
mechanism to tell it which action to take on failure.
With this patch, only failing devices are disabled not the whole port.
Transfer mode configuration must consider all devices on the port
regardless of failure status; otherwise, device selection timing can
be violoated resulting in malfunction. This patch makes
ata_dev_xfermask() consider disabled but present devices such that
device timing selection timing is honored.
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
ACK, but dropped due to dropping patch #1
As said in the above comment, this patch makes sure that present but
disabled devices are taken into account when determining transfer
mode. If IDENTIFY data is present, it is used; otherwise, PIO0 is
forced. I think this should be enough.
Several follow-up comments:
* Ideally, I think libata should re-read the identify data from the
device. This (a) makes sure PIO is working, and (b) tells us for
certain what mode the device is. That's fine for a follow-up patch
though, since few will exercise this code anyway.
* skipping ->post_set_mode() in this error case being discussing is
probably unwise.
BTW, got any PATA hardware lying about? Since you're wandering into
xfer mode territory, it would better to test PATA than SATA, as xfer
mode matters more in the PATA realm. Intel PATA should be fairly easy
to find, covered by ata_piix, and all the docs are on developer.intel.com.
Jeff
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