Re: [PATCH 1/2] usb: musb: Fix DMA for host mode

[Sergei Shtylyov]

On 02/02/2016 04:24 PM, Sergei Shtylyov wrote:

> > From: Cristian Birsan <cristian.birsan@xxxxxxxxxxxxx>
> >
> > Commit ac33cdb166811223cc (usb: musb: Remove ifdefs for musb_host_rx in
> > musb_host.c part5) introduces a problem setting DMA host mode.
>
>     scripts/checkpatch.pl now enforces certain commit citing style, yours
> doesn't quite match it.
>
> > This fixes the done condition that advances the musb schedule. Without this
> > patch the the msub_advance_schedule() is called immediately after receiving an
> > endpoint rx interrupt without waiting for the dma transfer to complete. As a
> > consequence when the dma complete interrupt arrives the in_qh member of hw_ep
> > is already null an the musb_host_rx() exits on !urb error case.
> >
> > Signed-off-by: Cristian Birsan <cristian.birsan@xxxxxxxxxxxxx>
> > Signed-off-by: Joshua Henderson <joshua.henderson@xxxxxxxxxxxxx>
> > ---
> >   drivers/usb/musb/musb_host.c |    5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> > index 795a45b..3fdc99b 100644
> > --- a/drivers/usb/musb/musb_host.c
> > +++ b/drivers/usb/musb/musb_host.c
> > @@ -1825,6 +1825,7 @@ void musb_host_rx(struct musb *musb, u8 epnum)
> >       u16            rx_csr, val;
> >       bool            iso_err = false;
> >       bool            done = false;
> > +    int            ret;
> >       u32            status;
> >       struct dma_channel    *dma;
> >       unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
> > @@ -2003,10 +2004,10 @@ void musb_host_rx(struct musb *musb, u8 epnum)
> >                   qh->offset,
> >                   urb->transfer_buffer_length);
> >
> > -            done = musb_rx_dma_in_inventra_cppi41(c, hw_ep, qh,
> > +            ret = musb_rx_dma_in_inventra_cppi41(c, hw_ep, qh,
> >                                     urb, xfer_len,
> >                                     iso_err);
> > -            if (done)
> > +            if (ret)
>
>     Hm, does that really fix anything?

   Looking again, I got the idea. However, there's no dire need for the new 
variable...
   (Handling Inventra and CPPI 4.1 DMA in the same code looks fishy. Too bad 
I wasn't able to push the CPPI 4.1 drivers myself.)

MBR, Sergei