From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA75E1A7AE3; Fri, 1 Aug 2025 12:00:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754049625; cv=none; b=t24kMPQ/pFBKE7C5t6VisVCalG6Wj9ZFeHYh73OcJ3D/GHLWSyEhz2CGJOG+pqIuaDNOXouemmyBDylmdWl3d1eOqV9UE24Kq1z3pzFt0Uye0LSIosun6QfVKePvMpr2sUhW6hgaoH3v2RuWB4NlgRV74nq3iquVD9Me/zyAhcE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754049625; c=relaxed/simple; bh=EZzubd/xjF898M9Natt5msPracSUglnvBpuGxbey28Y=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MmI02IabFy375bpD663UP9aSP3Ly1XAa5fHX+aCK3wUu3m2beKqlPCLE7fETRz6SZ1evDYhm8crCvBqsaaZPcHtV7Gauh1jqGn2jt/zOMvzgiLp70VXiKgI6nC6LJ+4+i21SpqoadrUovZjw6zvWKUj4Lyh6X3CsuUixmNLJcHQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=csSEQphS; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="csSEQphS" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 3245AB5; Fri, 1 Aug 2025 13:59:32 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1754049572; bh=EZzubd/xjF898M9Natt5msPracSUglnvBpuGxbey28Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=csSEQphShVW12KdVnTQnQgd8x4xM5grcNqKzGR+ppmLQ+JFyJUCU+zHhmagy7Z3hm NpCO8zEN1Kn5Zp/oSyG4PzbGQc9rVQYUc8NxohQ878NFh/I5Zywoz5Hp+ONwmSSZpf yJq8N7gHMTda3o4TRvZBBaBio2AAjXuKtD0aWOu0= Date: Fri, 1 Aug 2025 15:00:07 +0300 From: Laurent Pinchart To: Frank Li Cc: Konrad Dybcio , Vinod Koul , Sven Peter , Janne Grunau , Alyssa Rosenzweig , Neal Gompa , Ludovic Desroches , Florian Fainelli , Broadcom internal kernel review list , Ray Jui , Scott Branden , Paul Cercueil , Eugeniy Paltsev , Viresh Kumar , Andy Shevchenko , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Taichi Sugaya , Takao Orito , Andreas =?utf-8?Q?F=C3=A4rber?= , Manivannan Sadhasivam , Daniel Mack , Haojian Zhuang , Robert Jarzmik , Geert Uytterhoeven , Magnus Damm , Patrice Chotard , Linus Walleij , =?utf-8?Q?Am=C3=A9lie?= Delaunay , Maxime Coquelin , Alexandre Torgue , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Laxman Dewangan , Jon Hunter , Thierry Reding , Peter Ujfalusi , Kunihiko Hayashi , Masami Hiramatsu , Michal Simek , Rob Herring , Saravana Kannan , Martin =?utf-8?Q?Povi=C5=A1er?= , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , Kuninori Morimoto , Mukesh Kumar Savaliya , Viken Dadhaniya , Andi Shyti , Krzysztof Kozlowski , Conor Dooley , Bjorn Andersson , Marijn Suijten , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, asahi@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-mips@vger.kernel.org, imx@lists.linux.dev, linux-actions@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-sunxi@lists.linux.dev, linux-tegra@vger.kernel.org, devicetree@vger.kernel.org, linux-sound@vger.kernel.org, linux-i2c@vger.kernel.org, linux-spi@vger.kernel.org, Konrad Dybcio Subject: Re: [PATCH RFC 2/6] dmaengine: Make of_dma_request_slave_channel pass a cookie to of_xlate Message-ID: <20250801120007.GB4906@pendragon.ideasonboard.com> References: <20250730-topic-dma_genise_cookie-v1-0-b505c1238f9f@oss.qualcomm.com> <20250730-topic-dma_genise_cookie-v1-2-b505c1238f9f@oss.qualcomm.com> <20250730180417.GC21430@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Hi Frank, On Wed, Jul 30, 2025 at 02:37:54PM -0400, Frank Li wrote: > On Wed, Jul 30, 2025 at 09:04:17PM +0300, Laurent Pinchart wrote: > > On Wed, Jul 30, 2025 at 12:39:43PM -0400, Frank Li wrote: > > > On Wed, Jul 30, 2025 at 11:33:29AM +0200, Konrad Dybcio wrote: > > > > From: Konrad Dybcio > > > > > > > > The DMA subsystem attempts to make it theoretically possible to pair > > > > any DMA block with any user. While that's convenient from a > > > > codebase sanity perspective, some blocks are more intertwined. > > > > > > > > One such case is the Qualcomm GENI, where each wrapper contains a > > > > number of Serial Engine instances, each one of which can be programmed > > > > to support a different protocol (such as I2C, I3C, SPI, UART, etc.). > > > > > > > > The GPI DMA it's designed together with, needs to receive the ID of the > > > > protocol that's in use, to adjust its behavior accordingly. Currently, > > > > that's done through passing that ID through device tree, with each > > > > Serial Engine expressed NUM_PROTOCOL times, resulting in terrible > > > > dt-bindings that are full of useless copypasta. > > > > > > > > In a step to cut down on that, let the DMA user give the engine driver > > > > a hint at request time. > > > > > > > > Signed-off-by: Konrad Dybcio > > > > --- > > > > drivers/dma/amba-pl08x.c | 3 ++- > > > > drivers/dma/apple-admac.c | 3 ++- > > > > drivers/dma/at_hdmac.c | 6 ++++-- > > > > drivers/dma/at_xdmac.c | 3 ++- > > > > drivers/dma/bcm2835-dma.c | 3 ++- > > > > drivers/dma/dma-jz4780.c | 3 ++- > > > > drivers/dma/dmaengine.c | 20 +++++++++++++++++--- > > > > drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 3 ++- > > > > drivers/dma/dw/of.c | 3 ++- > > > > drivers/dma/ep93xx_dma.c | 6 ++++-- > > > > drivers/dma/fsl-edma-main.c | 6 ++++-- > > > > drivers/dma/img-mdc-dma.c | 3 ++- > > > > drivers/dma/imx-dma.c | 3 ++- > > > > drivers/dma/imx-sdma.c | 3 ++- > > > > drivers/dma/lgm/lgm-dma.c | 3 ++- > > > > drivers/dma/milbeaut-hdmac.c | 4 +++- > > > > drivers/dma/mmp_pdma.c | 3 ++- > > > > drivers/dma/mmp_tdma.c | 3 ++- > > > > drivers/dma/moxart-dma.c | 3 ++- > > > > drivers/dma/mxs-dma.c | 3 ++- > > > > drivers/dma/nbpfaxi.c | 3 ++- > > > > drivers/dma/of-dma.c | 18 +++++++++++------- > > > > drivers/dma/owl-dma.c | 3 ++- > > > > drivers/dma/pl330.c | 3 ++- > > > > drivers/dma/pxa_dma.c | 3 ++- > > > > drivers/dma/qcom/bam_dma.c | 3 ++- > > > > drivers/dma/qcom/gpi.c | 3 ++- > > > > drivers/dma/qcom/qcom_adm.c | 3 ++- > > > > drivers/dma/sh/rcar-dmac.c | 3 ++- > > > > drivers/dma/sh/rz-dmac.c | 3 ++- > > > > drivers/dma/sh/usb-dmac.c | 3 ++- > > > > drivers/dma/st_fdma.c | 3 ++- > > > > drivers/dma/ste_dma40.c | 3 ++- > > > > drivers/dma/stm32/stm32-dma.c | 3 ++- > > > > drivers/dma/stm32/stm32-dma3.c | 4 +++- > > > > drivers/dma/stm32/stm32-mdma.c | 3 ++- > > > > drivers/dma/sun4i-dma.c | 3 ++- > > > > drivers/dma/sun6i-dma.c | 3 ++- > > > > drivers/dma/tegra186-gpc-dma.c | 3 ++- > > > > drivers/dma/tegra20-apb-dma.c | 3 ++- > > > > drivers/dma/tegra210-adma.c | 3 ++- > > > > drivers/dma/ti/cppi41.c | 3 ++- > > > > drivers/dma/ti/edma.c | 3 ++- > > > > drivers/dma/ti/k3-udma.c | 3 ++- > > > > drivers/dma/uniphier-xdmac.c | 3 ++- > > > > drivers/dma/xilinx/xilinx_dma.c | 3 ++- > > > > drivers/dma/xilinx/xilinx_dpdma.c | 3 ++- > > > > drivers/dma/xilinx/zynqmp_dma.c | 3 ++- > > > > include/linux/dmaengine.h | 7 +++++++ > > > > include/linux/of_dma.h | 16 +++++++++------- > > > > sound/soc/apple/mca.c | 2 +- > > > > sound/soc/renesas/rcar/dma.c | 2 +- > > > > 52 files changed, 146 insertions(+), 68 deletions(-) > > > > > > > > diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c > > > > > > ... > > > > > > > const char *name) > > > > { > > > > diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h > > > > index fd706cdf255c61c82ce30ef9a2c44930bef34bc8..9f9bc4207b85d48d73c25aad4b362e7c84c01756 100644 > > > > --- a/include/linux/of_dma.h > > > > +++ b/include/linux/of_dma.h > > > > @@ -19,7 +19,7 @@ struct of_dma { > > > > struct list_head of_dma_controllers; > > > > struct device_node *of_node; > > > > struct dma_chan *(*of_dma_xlate) > > > > - (struct of_phandle_args *, struct of_dma *); > > > > + (struct of_phandle_args *, struct of_dma *, void *); > > > > > > I suggest pass down more informaiton, like client's dev point. So we can > > > auto create device link between client's dev and dma chan's device. > > > > Is .of_dma_xlate() really the right place to do that ? If you want to > > create a device link for PM reasons, isn't it better created when the > > channel is requested ? It should also be removed when the channel is > > freed. > > I remember just need record client device pointer here. > > > > > > > DMA Engineer device > > > DMA chan device > > > consumer clients' device. > > > > > > If consumer device runtime pm suspend can auto trigger DMA chan's device's > > > runtime pm function. > > > > > > It will simplifly DMA engine's run time pm manage. Currently many DMA run > > > time pm implement as, runtime_pm_get() when alloc and runtime_pm_put() at > > > free channel. But many devices request dma channel at probe, which make > > > dma engine work at always 'on' state. > > > > > > But ideally, dma chan should be resume only when it is used to transfer. > > > > This is exactly what I was going to mention after reading the last > > paragraph. Is there anything that prevents a DMA engine driver to > > perform a rutime PM get() when a transfer is submitted > > DMA description is a queue, It is hard to track each descriptor submit and > finished. espcially cycle buffer case. > > And according to dma engine API defination, submit a descriptor not > neccessary to turn on clock, maybe just pure software operation, such as > enqueue it to a software list. > > Many driver call dmaengine_submit() in irq context, submit new descriptor > when previous descriptor finished. runtime_pm_get() can NOT be called in > atomic context. > > And some driver submit many descripor advance. Only issue_transfer() is > actually trigger hardware to start transfer. > > Some client use cycle descripor, such audio devices. Some audio devices > have not free descriptor at their run time suspend function, just disable > audio devices's clocks. Audio devices run time suspend, which means no > one use this dma channel, dma channel can auto suspend if built device link > between audio device and dma chan devices. > > Some DMA client have not devices, such as memory to memory. for this kind > case, it need keep chan always on. > > issue_transfer() can be call in atomic context. but trigger hardware transfer > need clock and runtime_pm_get() can't be called in atomic context. > > Most case issue_transfer() is call in irq handle, which means device should > already be in runtime resume statue. DMA engine can safely access their > register if using device link. You have good points there, in particular the fact the issue_transfer() can be called in interrupt context. For me this calls for new DMA engine operations to "start/stop" the DMA engine (better names are likely needed) from a client perspective. > > and a put() when > > it completes ? (Logically speaking, the actual implementation would > > likely be a bit different in drivers, but the result would be similar.) > > > > > > void *(*of_dma_route_allocate) > > > > (struct of_phandle_args *, struct of_dma *); > > > > struct dma_router *dma_router; > > > > @@ -34,7 +34,7 @@ struct of_dma_filter_info { > > > > #ifdef CONFIG_DMA_OF > > > > extern int of_dma_controller_register(struct device_node *np, > > > > struct dma_chan *(*of_dma_xlate) > > > > - (struct of_phandle_args *, struct of_dma *), > > > > + (struct of_phandle_args *, struct of_dma *, void *), > > > > void *data); > > > > extern void of_dma_controller_free(struct device_node *np); > > > > > > > > @@ -45,16 +45,17 @@ extern int of_dma_router_register(struct device_node *np, > > > > #define of_dma_router_free of_dma_controller_free > > > > > > > > extern struct dma_chan *of_dma_request_slave_channel(struct device_node *np, > > > > - const char *name); > > > > + const char *name, > > > > + void *data); > > > > extern struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, > > > > - struct of_dma *ofdma); > > > > + struct of_dma *ofdma, void *data); > > > > extern struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec, > > > > - struct of_dma *ofdma); > > > > + struct of_dma *ofdma, void *data); > > > > > > > > #else > > > > static inline int of_dma_controller_register(struct device_node *np, > > > > struct dma_chan *(*of_dma_xlate) > > > > - (struct of_phandle_args *, struct of_dma *), > > > > + (struct of_phandle_args *, struct of_dma *, void *), > > > > void *data) > > > > { > > > > return -ENODEV; > > > > @@ -75,7 +76,8 @@ static inline int of_dma_router_register(struct device_node *np, > > > > #define of_dma_router_free of_dma_controller_free > > > > > > > > static inline struct dma_chan *of_dma_request_slave_channel(struct device_node *np, > > > > - const char *name) > > > > + const char *name, > > > > + void *data) > > > > { > > > > return ERR_PTR(-ENODEV); > > > > } > > > > diff --git a/sound/soc/apple/mca.c b/sound/soc/apple/mca.c > > > > index 5dd24ab90d0f052bb48f451cf009dc2e9128014d..43d48e4ac8161ee9955120fe64f7b911bfdfe1ca 100644 > > > > --- a/sound/soc/apple/mca.c > > > > +++ b/sound/soc/apple/mca.c > > > > @@ -926,7 +926,7 @@ static struct dma_chan *mca_request_dma_channel(struct mca_cluster *cl, unsigned > > > > char *name = devm_kasprintf(cl->host->dev, GFP_KERNEL, > > > > is_tx ? "tx%da" : "rx%db", cl->no); > > > > #endif > > > > - return of_dma_request_slave_channel(cl->host->dev->of_node, name); > > > > + return of_dma_request_slave_channel(cl->host->dev->of_node, name, NULL); > > > > > > > > } > > > > > > > > diff --git a/sound/soc/renesas/rcar/dma.c b/sound/soc/renesas/rcar/dma.c > > > > index 2035ce06fe4c4aeaa8620d817910a5319732fa58..dcbff2fc61a0472adea226371016a128563b3cd0 100644 > > > > --- a/sound/soc/renesas/rcar/dma.c > > > > +++ b/sound/soc/renesas/rcar/dma.c > > > > @@ -204,7 +204,7 @@ struct dma_chan *rsnd_dma_request_channel(struct device_node *of_node, char *nam > > > > } > > > > > > > > if (i == rsnd_mod_id_raw(mod) && (!chan)) > > > > - chan = of_dma_request_slave_channel(np, x); > > > > + chan = of_dma_request_slave_channel(np, x, NULL); > > > > i++; > > > > } > > > > -- Regards, Laurent Pinchart