-----Original Message-----
From: s.hauer at pengutronix.de [mailto:s.hauer at pengutronix.de]
Sent: 2018?7?11? 14:54
To: Robin Gong <redacted>
Cc: Vinod <vkoul@kernel.org>; dan.j.williams at intel.com;
shawnguo at kernel.org; Fabio Estevam [off-list ref];
linux at armlinux.org.uk; linux-arm-kernel at lists.infradead.org;
kernel at pengutronix.de; dmaengine at vger.kernel.org;
linux-kernel at vger.kernel.org; dl-linux-imx [off-list ref]
Subject: Re: [PATCH v1 3/4] dmaengine: imx-sdma: support dmatest

On Wed, Jul 11, 2018 at 06:37:02AM +0000, Robin Gong wrote:

quoted

quoted

-----Original Message-----
From: Vinod [mailto:vkoul at kernel.org]
Sent: 2018?7?10? 23:33
To: Robin Gong <redacted>
Cc: dan.j.williams at intel.com; shawnguo at kernel.org;
s.hauer at pengutronix.de; Fabio Estevam [off-list ref];
linux at armlinux.org.uk; linux-arm-kernel at lists.infradead.org;
kernel at pengutronix.de; dmaengine at vger.kernel.org;
linux-kernel at vger.kernel.org; dl-linux-imx [off-list ref]
Subject: Re: [PATCH v1 3/4] dmaengine: imx-sdma: support dmatest

On 11-07-18, 00:23, Robin Gong wrote:

quoted

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

quoted

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.

quoted

quoted

Signed-off-by: Robin Gong <redacted>
---
 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,

quoted

quoted

quoted

+	 * so jobs in dmaengine_slave_config need to be moved into

somewhere

quoted

quoted

quoted

+	 * before device_prep_dma_memcpy. Besides, dmatest never setup

chan

quoted

quoted

quoted

+	 * ->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):

quoted

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.

quoted

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?

Instead of doing heuristics to guess whether we are doing memcpy you could
instead make memcpy the default when slave_config is not called, i.e. drop the
if (!data) check completely.

Yes, for memcpy case, that's a good way, but how to warning the future case
Without setup 'chan->private'...

quoted

quoted

quoted

+		sdmac->word_size  =

sdmac->sdma->dma_device.copy_align;

quoted

quoted

quoted

+		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

The problem seems to be that we do not know whether we are doing memcpy
or not. Normally we get the information how a channel is to be configured in
dma_device->device_config, but this function is not called in the memcpy case.

An alternative might also be to do the setup in
dma_device->device_prep_dma_memcpy.

Yes, I've think about it before, but such prepare steps only needed in once time...

Sascha

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