Re: [PATCH v4 2/3] mmc: sdhci: add quirks for be to le byte swapping

[Angelo Dureghello <angelo.dureghello@xxxxxxxxxxx>]

Hi Adrian,

thanks for the feedbacks,
providing v5 in short, will run also checkpatch with "--strict".

On Fri, May 15, 2020 at 3:38 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> On 13/05/20 11:41 pm, Angelo Dureghello wrote:
> > Some controller as the ColdFire eshdc may require an endianness
> > byte swap, becouse DMA read endianness is not configurable.
> >
> > Signed-off-by: Angelo Dureghello <angelo.dureghello@xxxxxxxxxxx>
> > ---
> > Changes for v3:
> > - add post request callback
> > Changes for v4:
> > none
> > ---
> >  drivers/mmc/host/sdhci.c | 7 +++++++
> >  drivers/mmc/host/sdhci.h | 2 ++
> >  2 files changed, 9 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 3f716466fcfd..d3bfbb6e11d5 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -637,6 +637,13 @@ static int sdhci_pre_dma_transfer(struct sdhci_host *host,
> >                       sg_copy_to_buffer(data->sg, data->sg_len,
> >                                         host->bounce_buffer,
> >                                         length);
> > +
> > +                     /*
> > +                      * Endianness can't be swapped in the sg list,
> > +                      * since the sg list is processed again later on.
> > +                      */
>
> The data in the sg list must not be changed because we don't know how
> else it might be being used.  Maybe leave out the comment.
>
> > +                     if (host->ops->pre_dma_transfer)
> > +                             host->ops->pre_dma_transfer(host, data);
>
> Let's make this slightly more generic i.e.
>
>                         if (host->ops->copy_to_bounce_buffer) {
>                                 host->ops->copy_to_bounce_buffer(host, data);
>                         } else {
>                                 sg_copy_to_buffer(data->sg, data->sg_len,
>                                                   host->bounce_buffer,
>                                                   length);
>                         }
>
>
> >               }
> >               /* Switch ownership to the DMA */
> >               dma_sync_single_for_device(host->mmc->parent,
> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> > index 79dffbb731d3..076054308423 100644
> > --- a/drivers/mmc/host/sdhci.h
> > +++ b/drivers/mmc/host/sdhci.h
> > @@ -653,6 +653,8 @@ struct sdhci_ops {
> >       void    (*voltage_switch)(struct sdhci_host *host);
> >       void    (*adma_write_desc)(struct sdhci_host *host, void **desc,
> >                                  dma_addr_t addr, int len, unsigned int cmd);
> > +     void    (*pre_dma_transfer)(struct sdhci_host *host,
> > +                                 struct mmc_data *data);
> >       void    (*request_done)(struct sdhci_host *host,
> >                               struct mmc_request *mrq);
> >  };

Regards,
Angelo