Re: [PATCH/RFC 2/5] mmc: tmio: add complete to DMA ops

Geert Uytterhoeven
2017-06-16T07:09:33Z

Hi Simon,

On Fri, Jun 16, 2017 at 9:04 AM, Simon Horman <horms@verge.net.au> wrote:
> On Fri, Jun 16, 2017 at 08:25:12AM +0200, Geert Uytterhoeven wrote:
>> On Fri, Jun 16, 2017 at 8:06 AM, Simon Horman <horms@verge.net.au> wrote:
>> > On Fri, Jun 09, 2017 at 09:35:20AM +0200, Geert Uytterhoeven wrote:
>> >> On Thu, Jun 8, 2017 at 3:09 PM, Simon Horman <horms+renesas@verge.net.au> wrote:
>> >> > Add complete to DMA ops to allow DMAC implementation dependent
>> >> > handling of DMA completion.
>> >> >
>> >> > Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
>> >> > ---
>> >> > drivers/mmc/host/tmio_mmc.h | 1 +
>> >> > drivers/mmc/host/tmio_mmc_core.c | 10 ++++++++--
>> >> > 2 files changed, 9 insertions(+), 2 deletions(-)
>> >> >
>> >> > diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
>> >> > index 9c94b6eb9b49..82725f9de359 100644
>> >> > --- a/drivers/mmc/host/tmio_mmc.h
>> >> > +++ b/drivers/mmc/host/tmio_mmc.h
>> >> > @@ -121,6 +121,7 @@ struct tmio_mmc_dma_ops {
>> >> > struct tmio_mmc_data *pdata);
>> >> > void (*release)(struct tmio_mmc_host *host);
>> >> > void (*abort)(struct tmio_mmc_host *host);
>> >> > + void (*complete)(struct tmio_mmc_host *host);
>> >> > };
>> >> >
>> >> > struct tmio_mmc_host {
>> >> > diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
>> >> > index 0e76e099dc7f..26fe9bb64849 100644
>> >> > --- a/drivers/mmc/host/tmio_mmc_core.c
>> >> > +++ b/drivers/mmc/host/tmio_mmc_core.c
>> >> > @@ -86,6 +86,12 @@ static inline void tmio_mmc_abort_dma(struct tmio_mmc_host *host)
>> >> > host->dma_ops->abort(host);
>> >> > }
>> >> >
>> >> > +static inline void tmio_mmc_complete_dma(struct tmio_mmc_host *host)
>> >> > +{
>> >> > + if (host->dma_ops)
>> >> > + host->dma_ops->complete(host);
>> >>
>> >> I believe this will cause a crash and thus break bisection, as no driver
>> >> fills in the complete pointer yet.
>> >
>> > Indeed. And it seems to cause a panic on non-Gen3 users of the driver.
>> >
>> > I think the fix should be:
>> >
>> > diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
>> > index 26fe9bb64849..9ec2e933b6f0 100644
>> > --- a/drivers/mmc/host/tmio_mmc_core.c
>> > +++ b/drivers/mmc/host/tmio_mmc_core.c
>> > @@ -88,7 +88,7 @@ static inline void tmio_mmc_abort_dma(struct tmio_mmc_host *host)
>> >
>> > static inline void tmio_mmc_complete_dma(struct tmio_mmc_host *host)
>> > {
>> > - if (host->dma_ops)
>> > + if (host->dma_ops && host->dma_ops->complete)
>> > host->dma_ops->complete(host);
>> > }
>>
>> Is it? Now nothing will be completed?
>>
>> The old code did:
>>
>> complete(&host->dma_dataend);
>>
>> so perhaps
>>
>> else
>> complete(&host->dma_dataend);
>>
>> with the "else" branch to be deleted when all drivers that need it provide
>> their own complete callback?
>
> Thanks, I see that is still a problem.
>
> As there is only one other driver and its closerly related
> perhaps it could just implement the callback in this patch?

Yes, that sounds good to me.
Else you need 3 patches:
1. Introduced .complete field,
2. Update driver to provide .complete handledr,
3. Update generic code.

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