Re: [PATCH v1] dmaengine: imx-sdma: remove BD_INTR for channel0

From: Robin Gong <yibin.gong@nxp.com>
To: "thesven73@gmail.com" <thesven73@gmail.com>
Cc: "festevam@gmail.com" <festevam@gmail.com>,
	"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	dl-linux-imx <linux-imx@nxp.com>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
	"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	"m.olbrich@pengutronix.de" <m.olbrich@pengutronix.de>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v1] dmaengine: imx-sdma: remove BD_INTR for channel0
Date: Mon, 17 Jun 2019 01:42:24 +0000	[thread overview]
Message-ID: <1560764756.30149.5.camel@nxp.com> (raw)
In-Reply-To: <CAGngYiU_sNiAi0gYFEUg6=TfvUWH+6Nhid9PqYa6x+nb4UkVWA@mail.gmail.com>

On 2019-06-14 at 13:35 +0000, Sven Van Asbroeck wrote:
> Hi Robin, see comments inline.
> 
> On Fri, Jun 14, 2019 at 4:38 AM <yibin.gong@nxp.com> wrote:
> > 
> > 
> > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> > index deea9aa..b5a1ee2 100644
> > --- a/drivers/dma/imx-sdma.c
> > +++ b/drivers/dma/imx-sdma.c
> > @@ -742,7 +742,7 @@ static int sdma_load_script(struct sdma_engine
> > *sdma, void *buf, int size,
> >         spin_lock_irqsave(&sdma->channel_0_lock, flags);
> > 
> >         bd0->mode.command = C0_SETPM;
> > -       bd0->mode.status = BD_DONE | BD_INTR | BD_WRAP | BD_EXTD;
> > +       bd0->mode.status = BD_DONE | BD_WRAP | BD_EXTD;
> I tested this change on its own, and it seemed sufficient to make the
> crash
> disappear.
> 
> > 
> >         bd0->mode.count = size / 2;
> >         bd0->buffer_addr = buf_phys;
> >         bd0->ext_buffer_addr = address;
> > @@ -1064,7 +1064,7 @@ static int sdma_load_context(struct
> > sdma_channel *sdmac)
> >         context->gReg[7] = sdmac->watermark_level;
> > 
> >         bd0->mode.command = C0_SETDM;
> > -       bd0->mode.status = BD_DONE | BD_INTR | BD_WRAP | BD_EXTD;
> > +       bd0->mode.status = BD_DONE | BD_WRAP | BD_EXTD;
> This function isn't part of the firmware load path, so how can it be
> related
> to fixing the firmware crash?
Yes, that's not in your firmware load case, but I want to keep the same
behavior for all channel0 conditions, don't worry, harmless here. 
> 
> If this is an unrelated efficiency saving, maybe it should go into
> its
> own patch?
> Maybe we want bugfix patches to be as small and specific as possible,
> so they
> can more easily be backported to older kernels?
> 
> > 
> >         bd0->mode.count = sizeof(*context) / 4;
> >         bd0->buffer_addr = sdma->context_phys;
> >         bd0->ext_buffer_addr = 2048 + (sizeof(*context) / 4) *
> > channel;
> > --
> > 2.7.4
> > 
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