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SubjectRE: [PATCH v1 3/4] dmaengine: imx-sdma: support dmatest
Date

> -----Original Message-----
> From: Vinod [mailto:vkoul@kernel.org]
> Sent: 2018年7月10日 23:33
> To: Robin Gong <yibin.gong@nxp.com>
> Cc: dan.j.williams@intel.com; shawnguo@kernel.org;
> s.hauer@pengutronix.de; Fabio Estevam <fabio.estevam@nxp.com>;
> linux@armlinux.org.uk; linux-arm-kernel@lists.infradead.org;
> kernel@pengutronix.de; dmaengine@vger.kernel.org;
> linux-kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>
> Subject: Re: [PATCH v1 3/4] dmaengine: imx-sdma: support dmatest
>
> On 11-07-18, 00:23, Robin Gong wrote:
> > dmatest(memcpy) will never call dmaengine_slave_config before prep,
>
> and that should have been a hint to you that you should not expect that
>
> > so jobs in dmaengine_slave_config need to be moved into somewhere
> > before device_prep_dma_memcpy. Besides, dmatest never setup chan
> > ->private as other common case like uart/audio/spi will always setup
> > chan->private. Here check it to judge if it's dmatest case and do
> > jobs in slave_config.
>
> and you should not do anything for dmatest. Supporting it means memcpy
> implementation is not correct :)
Okay, I will any word about dmatest here since memcpy assume no calling
slave_config.
>
> >
> > Signed-off-by: Robin Gong <yibin.gong@nxp.com>
> > ---
> > drivers/dma/imx-sdma.c | 37 ++++++++++++++++++++++++++++---------
> > 1 file changed, 28 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c index
> > ed2267d..48f3749 100644
> > --- a/drivers/dma/imx-sdma.c
> > +++ b/drivers/dma/imx-sdma.c
> > @@ -1222,10 +1222,36 @@ static int sdma_alloc_chan_resources(struct
> > dma_chan *chan) {
> > struct sdma_channel *sdmac = to_sdma_chan(chan);
> > struct imx_dma_data *data = chan->private;
> > + struct imx_dma_data default_data;
> > int prio, ret;
> >
> > - if (!data)
> > - return -EINVAL;
> > + ret = clk_enable(sdmac->sdma->clk_ipg);
> > + if (ret)
> > + return ret;
> > + ret = clk_enable(sdmac->sdma->clk_ahb);
> > + if (ret)
> > + goto disable_clk_ipg;
> > + /*
> > + * dmatest(memcpy) will never call dmaengine_slave_config before prep,
> > + * so jobs in dmaengine_slave_config need to be moved into somewhere
> > + * before device_prep_dma_memcpy. Besides, dmatest never setup chan
> > + * ->private as other common cases like uart/audio/spi will setup
> > + * chan->private always. Here check it to judge if it's dmatest case
> > + * and do jobs in slave_config.
> > + */
> > + if (!data) {
> > + dev_warn(sdmac->sdma->dev, "dmatest is running?\n");
>
> why is that a warning!
Current SDMA driver assume filter function to set chan->private with specific data
(struct imx_dma_data dma_data)like below (sound/soc/fsl/fsl_asrc_dma.c):
static bool filter(struct dma_chan *chan, void *param)
{
if (!imx_dma_is_general_purpose(chan))
return false;
chan->private = param;
return true;
}

But in memcpy case, at lease dmatest case, no chan->private set in its filter function.
So here take dmatest a special case and do some prepare jobs for memcpy. But if the
Upper device driver call dma_request_channel() with their specific filter without
'chan->private' setting in the future. The warning message is a useful hint to them to
Add 'chan->private' in filter function. Or doc it somewhere?
>
> > + sdmac->word_size = sdmac->sdma->dma_device.copy_align;
> > + default_data.priority = 2;
> > + default_data.peripheral_type = IMX_DMATYPE_MEMORY;
> > + default_data.dma_request = 0;
> > + default_data.dma_request2 = 0;
> > + data = &default_data;
> > +
> > + sdma_config_ownership(sdmac, false, true, false);
> > + sdma_get_pc(sdmac, IMX_DMATYPE_MEMORY);
> > + sdma_load_context(sdmac);
> > + }
>
> this needs to be default for memcpy
>
> --
> ~Vinod
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