Hello Sergey,
On Sat, Feb 24, 2024 at 12:04:46AM +0300, Sergey Shtylyov wrote:
> On 2/19/24 6:29 PM, Niklas Cassel wrote:
> [...]
>
> >>> This reverts commit fd3a6837d8e18cb7be80dcca1283276290336a7a.
> >>>
> >>> Several users have signaled issues with commit fd3a6837d8e1 ("ata:
> >>> libata-core: Fix ata_pci_shutdown_one()") which causes failure of the
> >>> system SoC to go to a low power state. The reason for this problem
> >>> is not well understood but given that this patch is harmless with the
> >>> improvements to ata_dev_power_set_standby(), restore it to allow system
> >>> lower power state transitions.
> >>>
> >>> For regular system shutdown, ata_dev_power_set_standby() will be
> >>> executed twice: once the scsi device is removed and another when
> >>> ata_pci_shutdown_one() executes and EH completes unloading the devices.
> >>> Make the second call to ata_dev_power_set_standby() do nothing by using
> >>> ata_dev_power_is_active() and return if the device is already in
> >>> standby.
> >>>
> >>> Fixes: fd3a6837d8e1 ("ata: libata-core: Fix ata_pci_shutdown_one()")
> >>> Cc: stable@xxxxxxxxxxxxxxx
> >>> Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
> >>> ---
> >>> drivers/ata/libata-core.c | 75 +++++++++++++++++++++++----------------
> >>> 1 file changed, 45 insertions(+), 30 deletions(-)
> >>>
> >>> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> >>> index d9f80f4f70f5..20a366942626 100644
> >>> --- a/drivers/ata/libata-core.c
> >>> +++ b/drivers/ata/libata-core.c
> >>> @@ -2001,6 +2001,33 @@ bool ata_dev_power_init_tf(struct ata_device *dev, struct ata_taskfile *tf,
> >>> return true;
> >>> }
> >>>
> >>> +static bool ata_dev_power_is_active(struct ata_device *dev)
> >>> +{
> >>> + struct ata_taskfile tf;
> >>> + unsigned int err_mask;
> >>> +
> >>> + ata_tf_init(dev, &tf);
> >>> + tf.flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
> >>
> >> Why set ATA_TFLAG_ISADDR, BTW? This command doesn't use any taskfile
> >> regs but the device/head reg. Material for a fix, I guess... :-)
> >>
> >>> + tf.protocol = ATA_PROT_NODATA;
> >>> + tf.command = ATA_CMD_CHK_POWER;
> >>> +
> >> [...]
> >
> > Looking at the definition of the flag:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/libata.h?h=v6.8-rc5#n76
> >
> > "enable r/w to nsect/lba regs"
>
> I'm afraid this comment doesn't reflect the reality in its r/w part --
> if you look at e.g. ata_sff_tf_read(), you'll see that it always reads
> all the legacy taskfile and only checks ATA_TFLAG_LBA48 in order to
> determine whether it should read the HOBs as well...
Considering that you have experience with cleaning up a similar mess in
drivers/ide, patches for drivers/ata which fixes the comment and the
functions needlessly setting the ATA_TFLAG_DEVICE flag is more than
welcome.
>From a quick look, there appears to be quite a few functions (in
addition to ata_dev_power_is_active()) which needlessly sets this flag.
Kind regards,
Niklas
