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

Simon Horman
2017-06-16T07:13:55Z

On Fri, Jun 16, 2017 at 09:09:31AM +0200, Geert Uytterhoeven wrote:
> 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.

Yes, and 3 patch seems a bit excessive in this case.

Sorry for letting this bug creep in to renesas-drivers.
Do you want a patch against your tree? I will plan to post v2 of
this patchset soon in any case.