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

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Marek Vasut <marek.vasut@gmail.com>
Cc: "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	Marek Vasut <marek.vasut+renesas@gmail.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: Re: [PATCH 14/14] gpio: pca953x: Restore registers after suspend/resume cycle
Date: Tue, 18 Dec 2018 13:57:54 +0100	[thread overview]
Message-ID: <CAMuHMdVRW49R015G+t5zw57z-JMcfbJ+6mAthkDD9P4-edRxtA@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdUc4v5C-KCkuAQ_nsbcjWjYDyUggPDgi1tivMbcRcCNDQ@mail.gmail.com>

Hi Marek,

On Mon, Dec 3, 2018 at 6:55 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Sun, Dec 2, 2018 at 8:36 PM Marek Vasut <marek.vasut@gmail.com> 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@gmail.com>
>
> 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().

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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