Re: [PATCH 11/15] tty: msm_serial: use dmaengine_prep_slave_sg()

[Jiri Slaby]

On 19. 04. 24, 10:00, Marek Szyprowski wrote:
> On 19.04.2024 09:53, Jiri Slaby wrote:
> > On 19. 04. 24, 9:43, Jiri Slaby wrote:
> > > On 17. 04. 24, 14:45, Marek Szyprowski wrote:
> > > > I alse tried to change the "if (dma->mapped)" check in
> > > > msm_start_tx() to:
> > > >
> > > > 1. if (dma->tx_sg.length)
> > > >
> > > > 2. if (dma->tx_sg.page_link & ~SG_PAGE_LINK_MASK)
> > > >
> > > > but none of the above worked what is really strange and
> > > > incomprehensible
> > > > for me.
> > >
> > > Aaaah, nevermind, what about this?
> > >
> > > Two bugs:
> > > 1) dma_map_sg() returns the number of mapped entries. Not zero!
> > > 2) And I forgot to zero tx_sg in case of error.
> > >
> > > --- a/drivers/tty/serial/msm_serial.c
> > > +++ b/drivers/tty/serial/msm_serial.c
> > > @@ -506,8 +506,8 @@ static int msm_handle_tx_dma(struct msm_port
> > > *msm_port, unsigned int count)
> > >           kfifo_dma_out_prepare(&tport->xmit_fifo, &dma->tx_sg, 1,
> > > count);
> > >
> > >           ret = dma_map_sg(port->dev, &dma->tx_sg, 1, dma->dir);
> > > -       if (ret)
> > > -               return ret;
> > > +       if (!ret)
> >
> > Still wrong, ret = -EIO missing in here.
>
> "if (ret <= 0)" seems to be better here.

It returns unsigned, so I have a better patch. Will send in a second.

> Indeed this fixed the issue. I checked the code many times, but I missed
> this dma_map_sg() return value issue.

Perfect!

> Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>

Could you test that one too :)?

thanks,
--
js
suse labs