Hi Wolfram-san again,
> From: Yoshihiro Shimoda, Sent: Tuesday, December 15, 2020 10:32 AM
> > From: Wolfram Sang, Sent: Tuesday, December 15, 2020 12:50 AM
> > On Fri, Dec 04, 2020 at 10:17:33PM +0900, Yoshihiro Shimoda wrote:
> > > /*
> > > * Specification of this driver:
> > > * - host->chan_{rx,tx} will be used as a flag of enabling/disabling the dma
> > > @@ -172,6 +178,47 @@ renesas_sdhi_internal_dmac_dataend_dma(struct tmio_mmc_host *host) {
> > > tasklet_schedule(&priv->dma_priv.dma_complete);
> > > }
> > >
> > > +/* Should not use host->sg_ptr/sg_len in the following function */
> >
> > Maybe a short explanation why we shouldn't use the functions?
>
> I tried to update the comment as below:
> /*
> * tmio_mmc_request() only sets host->sg_{ptr,len} and
> * renesas_sdhi_internal_dmac_pre_req() doesn't set host->sg_{ptr,len} so that
> * we should not use the values in the following function.
> */
>
> Hmm... Perhaps, I should modify the code to use host->sg_{ptr,len}
> in both paths (.request() and .pre_req()) and remove this comments.
> So, I'll try to modify. I guess tmio_mmc_init_sg() is called in pre_req(),
> we can use host->sg_{ptr,len}.
I'm sorry. I was completely wrong. If we use {pre,post}_req,
the MMC core will call pre_req() twice with each mmc_data before
pre_req() is called. So that, second pre_req() will overwrite
the host->sg_ptr. So, we should not use host->sg_ptr here.
So, I'll update the comments like below.
/*
* Since pre_req() will be called twice before post_req() is called,
* host->sg_ptr will be overwritten by second pre_req(). So, to use
* suitable sg pointer, should use data->sg/sg_len instead of
* host->sg_ptr/sg_len.
*/
Best regards,
Yoshihiro Shimoda
