Re: [PATCH 14/14] gpio: pca953x: Restore registers after suspend/resume cycle

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Marek,

On Tue, Dec 18, 2018 at 1:57 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> On Mon, Dec 3, 2018 at 6:55 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> > On Sun, Dec 2, 2018 at 8:36 PM Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> > > It is possible that the PCA953x is powered down during suspend.
> > > Use regmap cache to assure the registers in the PCA953x are in
> > > line with the driver state after resume.
> > >
> > > Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
> >
> > Thanks for your series!
> >
> > Background info: the main motivation for this series is to make sure SATA
> > keeps working after system suspend/resume on the Salvator-XS development
> > board, where the SATA functionality is configured using a gpio hog.
> >
> > With your series applied, the SATA link seems to be functional after resume.
> > Dmesg difference:
> >
> >      ata1: link resume succeeded after 1 retries
> >     -ata1: SATA link down (SStatus 0 SControl 300)
> >     -ata1: link resume succeeded after 1 retries
> >     -ata1: SATA link down (SStatus 0 SControl 300)
> >     -ata1: link resume succeeded after 1 retries
> >     -ata1: SATA link down (SStatus 0 SControl 300)
> >     -ata1.00: disabled
> >     -sd 0:0:0:0: rejecting I/O to offline device
> >     +ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
> >     +ata1.00: configured for UDMA/133
> >
> > However, when trying to read from an attached hard drive, it fails:
> >
> >     ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
> >     ata1.00: failed command: READ DMA
> >     ata1.00: cmd c8/00:20:00:00:00/00:00:00:00:00/e0 tag 0 dma 16384 in
> >              res 40/00:00:01:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)
> >     ata1.00: status: { DRDY }
> >     ata1: hard resetting link
> >     ata1: link resume succeeded after 1 retries
> >     ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
> >     ata1.00: configured for UDMA/133
> >     sd 0:0:0:0: [sda] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x00
> > driverbyte=0x08
> >     sd 0:0:0:0: [sda] tag#0 Sense Key : 0x5 [current]
> >     sd 0:0:0:0: [sda] tag#0 ASC=0x21 ASCQ=0x4
> >     sd 0:0:0:0: [sda] tag#0 CDB: opcode=0x28 28 00 00 00 00 00 00 00 20 00
> >     print_req_error: I/O error, dev sda, sector 0
> >     ata1: EH complete
> >     ...
> >     Buffer I/O error on dev sda, logical block 0, async page read
> >
> > Does SATA work for you after resume!
> > This could still be an issue in the sata_rcar driver.
>
> FTR, it wasn't. With V3 as present in gpio/for-next, SATA works fine after
> resume.
> Major difference seems to be the use of regmap_bulk_read() vs. regmap_read().

I think I found the real reason: my failing config had IPMMU enabled for SATA
virtualization, but the IPMMU driver doesn't handle suspend/resume yet.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds