Re: [PATCH] ata: sata_dwc_460ex: fix sata_dwc_460ex when using dma transfers

[Andy Shevchenko]

On Wed, Apr 6, 2016 at 6:33 PM, Christian Lamparter
<chunkeey@xxxxxxxxxxxxxx> wrote:
> This patch allows sata_dwc_460ex to work with non-ncq, dma i/o.
> Previously, the driver dumped the following warning:
>
>  ------------[ cut here ]------------
> WARNING: at c01f3d50 [verbose debug info unavailable]
> CPU: 0 PID: 315 Comm: kworker/u2:2 Not tainted 4.4.6 #18
> Workqueue: events_unbound async_run_entry_fn
> NIP [c01f3d50] ata_sff_qc_issue+0x1d8/0x204
> LR [c01f3bbc] ata_sff_qc_issue+0x44/0x204
> Call Trace:
> [cf6a98c0] [c01f3bbc] ata_sff_qc_issue+0x44/0x204 (unreliable)
> [cf6a98e0] [c01f4e38] sata_dwc_qc_issue+0x270/0x298
> [cf6a9950] [c01e24f4] ata_qc_issue+0x2f0/0x364
>
> and was unable to access the drive. The issue is that
> ata_sff_qc_issue can only handle PIO. This patch replaces
> the it with ata_bmdma_qc_issue which handles DMA transfers
> and can fallback to PIO when needed.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Christian Lamparter <chunkeey@xxxxxxxxxxxxxx>
> ---
> Note: I have a system with a APM82181 (which is a ppc460ex derivative).
> It's the SoC in the WD MyBook Live NAS.
>
> The driver has other issues as well... e.g:
>
> Unable to handle kernel paging request for data at address 0x00000004
> Faulting instruction address: 0xc01f2640
> Oops: Kernel access of bad area, sig: 11 [#1]
> CPU: 0 PID: 1 Comm: swapper Not tainted 4.4.6 #42
> NIP [c01f2640] sata_dwc_probe+0x1a8/0x2dc
> LR [c01f2640] sata_dwc_probe+0x1a8/0x2dc
> Call Trace:
> [cf435d60] [c01f2640] sata_dwc_probe+0x1a8/0x2dc (unreliable)
> [cf435dc0] [c01c5728] platform_drv_probe+0x34/0x70
> (This is due to hsdev->dma being NULL, as it was never allocated
> or set).
>
> However, this has been fixed (including fixes to dwc's
> DMA) by Mans Rullgard. His repo is available from:
> <https://bitbucket.org/mansr/linux-dwc/branch/dwc-sata>
>
> Note2: NCQ seems to freezes the controller. Not sure what's
> going on. I can post a separate patch to disable it, if requested.

Thanks for the patch. Like I said before please check the branch we
have and jump in in testing / suggesting better fixes. Please, also
keep MÃns and me in Cc list regarding this driver.

> ---
>  drivers/ata/sata_dwc_460ex.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
> index e7a47aa..234f50d 100644
> --- a/drivers/ata/sata_dwc_460ex.c
> +++ b/drivers/ata/sata_dwc_460ex.c
> @@ -1113,7 +1113,9 @@ static unsigned int sata_dwc_qc_issue(struct ata_queued_cmd *qc)
>                 sata_dwc_exec_command_by_tag(ap, &qc->tf, qc->tag,
>                                              SATA_DWC_CMD_ISSUED_PEND);
>         } else {
> -               ata_sff_qc_issue(qc);
> +               /* Sync ata_port with qc->tag */
> +               ap->link.active_tag = qc->tag;
> +               return ata_bmdma_qc_issue(qc);
>         }
>         return 0;
>  }
> --
> 2.8.0.rc3
>



-- 
With Best Regards,
Andy Shevchenko