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From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
To: Vinod Koul <vkoul@kernel.org>, Viresh Kumar <vireshk@kernel.org>,
	Dan Williams <dan.j.williams@intel.com>
Cc: Serge Semin <Sergey.Semin@baikalelectronics.ru>,
	Serge Semin <fancer.lancer@gmail.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Arnd Bergmann <arnd@arndb.de>, Rob Herring <robh+dt@kernel.org>,
	<linux-mips@vger.kernel.org>, <devicetree@vger.kernel.org>,
	<dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH v7 05/11] dmaengine: Introduce DMA-device device_caps callback
Date: Fri, 10 Jul 2020 01:45:44 +0300
Message-ID: <20200709224550.15539-6-Sergey.Semin@baikalelectronics.ru> (raw)
In-Reply-To: <20200709224550.15539-1-Sergey.Semin@baikalelectronics.ru>

There are DMA devices (like ours version of Synopsys DW DMAC) which have
DMA capabilities non-uniformly redistributed between the device channels.
In order to provide a way of exposing the channel-specific parameters to
the DMA engine consumers, we introduce a new DMA-device callback. In case
if provided it gets called from the dma_get_slave_caps() method and is
able to override the generic DMA-device capabilities.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: devicetree@vger.kernel.org

---

Changelog v3:
- This is a new patch created as a result of the discussion with Vinod and
  Andy in the framework of DW DMA burst and LLP capabilities.

Changelog v5:
- Add in-line comment at the point of the device_caps callback invocation.
- Add doc-comment for the device_caps member of struct dma_device.
---
 drivers/dma/dmaengine.c   | 10 ++++++++++
 include/linux/dmaengine.h |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index ad56ad58932c..ed1fd376f1a5 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -599,6 +599,16 @@ int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
 	caps->cmd_resume = !!device->device_resume;
 	caps->cmd_terminate = !!device->device_terminate_all;
 
+	/*
+	 * DMA engine device might be configured with non-uniformly
+	 * distributed slave capabilities per device channels. In this
+	 * case the corresponding driver may provide the device_caps
+	 * callback to override the generic capabilities with
+	 * channel-specific ones.
+	 */
+	if (device->device_caps)
+		device->device_caps(chan, caps);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dma_get_slave_caps);
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index a7e4d8dfdd19..298b721c8b9f 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -799,6 +799,8 @@ struct dma_filter {
  *	be called after period_len bytes have been transferred.
  * @device_prep_interleaved_dma: Transfer expression in a generic way.
  * @device_prep_dma_imm_data: DMA's 8 byte immediate data to the dst address
+ * @device_caps: May be used to override the generic DMA slave capabilities
+ *	with per-channel specific ones
  * @device_config: Pushes a new configuration to a channel, return 0 or an error
  *	code
  * @device_pause: Pauses any transfer happening on a channel. Returns
@@ -899,6 +901,8 @@ struct dma_device {
 		struct dma_chan *chan, dma_addr_t dst, u64 data,
 		unsigned long flags);
 
+	void (*device_caps)(struct dma_chan *chan,
+			    struct dma_slave_caps *caps);
 	int (*device_config)(struct dma_chan *chan,
 			     struct dma_slave_config *config);
 	int (*device_pause)(struct dma_chan *chan);
-- 
2.26.2


  parent reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-09 22:45 [PATCH RESEND v7 00/11] dmaengine: dw: Take Baikal-T1 SoC DW DMAC peculiarities into account Serge Semin
2020-07-09 22:45 ` [PATCH v7 01/11] dt-bindings: dma: dw: Convert DW DMAC to DT binding Serge Semin
2020-07-09 22:45 ` [PATCH v7 02/11] dt-bindings: dma: dw: Add max burst transaction length property Serge Semin
2020-07-09 22:45 ` [PATCH v7 03/11] dmaengine: Introduce min burst length capability Serge Semin
2020-07-09 22:45 ` [PATCH v7 04/11] dmaengine: Introduce max SG list entries capability Serge Semin
2020-07-10  8:31   ` Peter Ujfalusi
2020-07-10  9:27     ` Serge Semin
2020-07-10 11:51       ` Peter Ujfalusi
2020-07-10 16:14         ` Serge Semin
2020-07-15 11:13           ` Vinod Koul
2020-07-15 17:08             ` Serge Semin
2020-07-17  8:14               ` Vinod Koul
2020-07-17 12:36                 ` Serge Semin
2020-07-09 22:45 ` Serge Semin [this message]
2020-07-10  8:45   ` [PATCH v7 05/11] dmaengine: Introduce DMA-device device_caps callback Andy Shevchenko
2020-07-10  9:38     ` Serge Semin
2020-07-13  6:51       ` Vinod Koul
2020-07-13 20:13         ` Serge Semin
2020-07-13 20:55       ` Dave Jiang
2020-07-14 16:08         ` Vinod Koul
2020-07-14 16:18           ` Dave Jiang
2020-07-14 16:29             ` Serge Semin
2020-07-14 16:49               ` Dave Jiang
2020-07-09 22:45 ` [PATCH v7 06/11] dmaengine: dw: Take HC_LLP flag into account for noLLP auto-config Serge Semin
2020-07-09 22:45 ` [PATCH v7 07/11] dmaengine: dw: Set DMA device max segment size parameter Serge Semin
2020-07-09 22:45 ` [PATCH v7 08/11] dmaengine: dw: Add dummy device_caps callback Serge Semin
2020-07-10  8:51   ` Andy Shevchenko
2020-07-10  8:52     ` Andy Shevchenko
2020-07-10  9:45     ` Serge Semin
2020-07-15 12:01       ` Vinod Koul
2020-07-09 22:45 ` [PATCH v7 09/11] dmaengine: dw: Initialize min and max burst DMA device capability Serge Semin
2020-07-09 22:45 ` [PATCH v7 10/11] dmaengine: dw: Introduce max burst length hw config Serge Semin
2020-07-09 22:45 ` [PATCH v7 11/11] dmaengine: dw: Initialize max_sg_nents capability Serge Semin

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