> -----Original Message----- > From: Vinod [mailto:vkoul@xxxxxxxxxx] > Sent: 2018年7月11日 15:19 > To: s.hauer@xxxxxxxxxxxxxx > Cc: Robin Gong <yibin.gong@xxxxxxx>; dan.j.williams@xxxxxxxxx; > shawnguo@xxxxxxxxxx; Fabio Estevam <fabio.estevam@xxxxxxx>; > linux@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > kernel@xxxxxxxxxxxxxx; dmaengine@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx> > Subject: Re: [PATCH v1 3/4] dmaengine: imx-sdma: support dmatest > > On 11-07-18, 08:53, s.hauer@xxxxxxxxxxxxxx wrote: > > On Wed, Jul 11, 2018 at 06:37:02AM +0000, Robin Gong wrote: > > > > > > > -----Original Message----- > > > > From: Vinod [mailto:vkoul@xxxxxxxxxx] > > > > Sent: 2018年7月10日 23:33 > > > > To: Robin Gong <yibin.gong@xxxxxxx> > > > > Cc: dan.j.williams@xxxxxxxxx; shawnguo@xxxxxxxxxx; > > > > s.hauer@xxxxxxxxxxxxxx; Fabio Estevam <fabio.estevam@xxxxxxx>; > > > > linux@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > > > > kernel@xxxxxxxxxxxxxx; dmaengine@xxxxxxxxxxxxxxx; > > > > linux-kernel@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx> > > > > 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 > > > > > chan->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@xxxxxxx> > > > > > --- > > > > > 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? > > > > 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. > > > > > > > > > > > + 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 > > > > 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. > > Not really true, device_config only provides parameters to be configured for > next slave transaction > > > An alternative might also be to do the setup in > dma_device->device_prep_dma_memcpy. > > Precisely, see how other drivers do this > > Let's roll back a bit and foresee why is this required. > > In case of memcpy, you need to tell DMA to do transfer from src to dstn and > size. Additional parameters like buswidth etc should be derived for maximum > throughput (after all we are dma, people want it to be done > fastest) > > Now for slave, you are interfacing with a peripheral and don't know how that is > setup. So you need to match the parameters, otherwise you get overflow or > underflow and hence need for device_config > > Please do not derive additional notions from these, please do not assume > anything else, unless provided in documentation :) I will move such prepare jobs from slave_config to device_prep_dma_memcpy Instead of device_alloc_chan_resources as I did in v1, thus we have no 'chan->private' issue, just like drivers/dma/stm32-mdma.c. The only limitation is those prepare jobs (some register setting) will be done every time memcpy instead of only one time in slave_config or v1 case. Is that ok? > > In doubt, just ask! > > HTH > -- > ~Vinod ��.n��������+%������w��{.n��������)�)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
