Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755555AbcJ3CGw convert rfc822-to-8bit (ORCPT ); Sat, 29 Oct 2016 22:06:52 -0400 Received: from smtp.csie.ntu.edu.tw ([140.112.30.61]:55824 "EHLO smtp.csie.ntu.edu.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753772AbcJ3CGt (ORCPT ); Sat, 29 Oct 2016 22:06:49 -0400 MIME-Version: 1.0 In-Reply-To: <20161027175154.v4kuhyvm3r5n6tdo@lukather> References: <3a2404510b5f8b16ae3bb193982d70f158700b2b.1475571575.git.mylene.josserand@free-electrons.com> <20161004124011.d7f5754a082d5f17d5185fc4@free.fr> <20161004165553.GS5228@lukather> <20161023183107.5b75b6aad62853378713299f@free.fr> <20161027175154.v4kuhyvm3r5n6tdo@lukather> From: Chen-Yu Tsai Date: Sun, 30 Oct 2016 10:06:20 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 01/14] dma: sun6i-dma: Add burst case of 4 To: Maxime Ripard Cc: Jean-Francois Moine , =?UTF-8?Q?Myl=C3=A8ne_Josserand?= , Vinod Koul , Chen-Yu Tsai , Mike Turquette , Stephen Boyd , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , Lee Jones , Mark Rutland , Rob Herring , Thomas Petazzoni , devicetree , Linux-ALSA , linux-kernel , linux-sunxi , Alexandre Belloni , dmaengine@vger.kernel.org, linux-clk , linux-arm-kernel Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6487 Lines: 156 Hi, On Fri, Oct 28, 2016 at 1:51 AM, Maxime Ripard wrote: > On Sun, Oct 23, 2016 at 06:31:07PM +0200, Jean-Francois Moine wrote: >> On Tue, 4 Oct 2016 18:55:54 +0200 >> Maxime Ripard wrote: >> >> > On Tue, Oct 04, 2016 at 12:40:11PM +0200, Jean-Francois Moine wrote: >> > > On Tue, 4 Oct 2016 11:46:14 +0200 >> > > Mylène Josserand wrote: >> > > >> > > > Add the case of a burst of 4 which is handled by the SoC. >> > > > >> > > > Signed-off-by: Mylène Josserand >> > > > --- >> > > > drivers/dma/sun6i-dma.c | 2 ++ >> > > > 1 file changed, 2 insertions(+) >> > > > >> > > > diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c >> > > > index 8346199..0485204 100644 >> > > > --- a/drivers/dma/sun6i-dma.c >> > > > +++ b/drivers/dma/sun6i-dma.c >> > > > @@ -240,6 +240,8 @@ static inline s8 convert_burst(u32 maxburst) >> > > > switch (maxburst) { >> > > > case 1: >> > > > return 0; >> > > > + case 4: >> > > > + return 1; >> > > > case 8: >> > > > return 2; >> > > > default: >> > > > -- >> > > > 2.9.3 >> > > >> > > This patch has already been rejected by Maxime in the threads >> > > http://www.spinics.net/lists/dmaengine/msg08610.html >> > > and >> > > http://www.spinics.net/lists/dmaengine/msg08719.html >> > > >> > > I hope you will find the way he wants for this maxburst to be added. >> > >> > I was talking about something along these lines (not tested): >> >> I wonder why you don't submit this yourself. > > I thought you were the one who cared. You asked for what I had in > mind, here it is. > >> > -------8<--------- >> > diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c >> > index 83461994e418..573ac4608293 100644 >> > --- a/drivers/dma/sun6i-dma.c >> > +++ b/drivers/dma/sun6i-dma.c >> > @@ -240,6 +240,8 @@ static inline s8 convert_burst(u32 maxburst) >> > switch (maxburst) { >> > case 1: >> > return 0; >> > + case 4: >> > + return 1; >> > case 8: >> > return 2; >> > default: >> > @@ -1110,11 +1112,19 @@ static int sun6i_dma_probe(struct platform_device *pdev) >> > sdc->slave.dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) | >> > BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | >> > BIT(DMA_SLAVE_BUSWIDTH_4_BYTES); >> > + sdc->slave.dst_bursts = BIT(1) | BIT(8); >> > + sdc->slave.src_bursts = BIT(1) | BIT(8); >> > sdc->slave.directions = BIT(DMA_DEV_TO_MEM) | >> > BIT(DMA_MEM_TO_DEV); >> > sdc->slave.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST; >> > sdc->slave.dev = &pdev->dev; >> > >> > + if (of_device_is_compatible(pdev->dev.of_node, >> > + "allwinner,sun8i-h3-dma")) { >> > + sdc->slave.dst_bursts |= BIT(4); >> > + sdc->slave.src_bursts |= BIT(4); >> > + } >> > + >> > sdc->pchans = devm_kcalloc(&pdev->dev, sdc->cfg->nr_max_channels, >> > sizeof(struct sun6i_pchan), GFP_KERNEL); >> > if (!sdc->pchans) >> > diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h >> > index cc535a478bae..f7bbec24bb58 100644 >> > --- a/include/linux/dmaengine.h >> > +++ b/include/linux/dmaengine.h >> > @@ -673,6 +673,8 @@ struct dma_filter { >> > * each type of direction, the dma controller should fill (1 << >> > * ) and same should be checked by controller as well >> > * @max_burst: max burst capability per-transfer >> > + * @dst_bursts: bitfield of the available burst sizes for the destination >> > + * @src_bursts: bitfield of the available burst sizes for the source >> >> You did not define dst_bursts nor src_bursts. >> >> > * @residue_granularity: granularity of the transfer residue reported >> > * by tx_status >> > * @device_alloc_chan_resources: allocate resources and return the >> > @@ -800,6 +802,14 @@ struct dma_device { >> > static inline int dmaengine_slave_config(struct dma_chan *chan, >> > struct dma_slave_config *config) >> > { >> > + if (config->src_maxburst && config->device->src_bursts && >> > + !(BIT(config->src_maxburst) & config->device->src_bursts)) >> >> The maxburst may be as big as 4Kibytes, then, I am not sure that this >> code will work! >> >> > + return -EINVAL; >> > + >> > + if (config->dst_maxburst && config->device->dst_bursts && >> > + !(BIT(config->dst_maxburst) & config->device->dst_bursts)) >> > + return -EINVAL; >> > + >> > if (chan->device->device_config) >> > return chan->device->device_config(chan, config); >> > -------8<------------ >> >> Yes, I know that the burst size is always a power of 2. >> The best way to check it would be to change the {src,dts}_maxburst to a >> bitmap of the possible bursts as 0x0d for 1,4 and 8 bytes. But this >> asks for a lot of changes... > > To be honest, I'm not really a big fan of those tree wide changes > without any way to maintain compatibility. It ends up in a single, > huge patch if we want to maintain bisectability that just isn't > reviewable. Looking at the dmaengine API, I believe we got it wrong. max_burst in dma_slave_config denotes the largest amount of data a single transfer should be, as described in dmaengine.h: * @src_maxburst: the maximum number of words (note: words, as in * units of the src_addr_width member, not bytes) that can be sent * in one burst to the device. Typically something like half the * FIFO depth on I/O peripherals so you don't overflow it. This * may or may not be applicable on memory sources. * @dst_maxburst: same as src_maxburst but for destination target * mutatis mutandis. The DMA engine driver should be free to select whatever burst size that doesn't exceed this. So for max_burst = 4, the driver can select burst = 4 for controllers that do support it, or burst = 1 for those that don't, and do more bursts. This also means we can increase max_burst for the audio codec, as the FIFO is 64 samples deep for stereo, or 128 samples for mono. If we agree on the above I can send some patches for this. Regards ChenYu