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From: Ulf Hansson <ulf.hansson@linaro.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	linux-kernel@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>, Christoph Hellwig <hch@lst.de>,
	Russell King <linux@armlinux.org.uk>,
	Linus Walleij <linus.walleij@linaro.org>,
	Vinod Koul <vkoul@kernel.org>, Haibo Chen <haibo.chen@nxp.com>,
	Ludovic Barre <ludovic.barre@st.com>,
	linux-arm-kernel@lists.infradead.org, dmaengine@vger.kernel.org,
	Ulf Hansson <ulf.hansson@linaro.org>,
	stable@vger.kernel.org
Subject: [PATCH 1/2] driver core: platform: Initialize dma_parms for platform devices
Date: Wed, 25 Mar 2020 12:34:06 +0100	[thread overview]
Message-ID: <20200325113407.26996-2-ulf.hansson@linaro.org> (raw)
In-Reply-To: <20200325113407.26996-1-ulf.hansson@linaro.org>

It's currently the platform driver's responsibility to initialize the
pointer, dma_parms, for its corresponding struct device. The benefit with
this approach allows us to avoid the initialization and to not waste memory
for the struct device_dma_parameters, as this can be decided on a case by
case basis.

However, it has turned out that this approach is not very practical.  Not
only does it lead to open coding, but also to real errors. In principle
callers of dma_set_max_seg_size() doesn't check the error code, but just
assumes it succeeds.

For these reasons, let's do the initialization from the common platform bus
at the device registration point. This also follows the way the PCI devices
are being managed, see pci_device_add().

Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/base/platform.c         | 1 +
 include/linux/platform_device.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index b5ce7b085795..46abbfb52655 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -512,6 +512,7 @@ int platform_device_add(struct platform_device *pdev)
 		pdev->dev.parent = &platform_bus;
 
 	pdev->dev.bus = &platform_bus_type;
+	pdev->dev.dma_parms = &pdev->dma_parms;
 
 	switch (pdev->id) {
 	default:
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 041bfa412aa0..81900b3cbe37 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -25,6 +25,7 @@ struct platform_device {
 	bool		id_auto;
 	struct device	dev;
 	u64		platform_dma_mask;
+	struct device_dma_parameters dma_parms;
 	u32		num_resources;
 	struct resource	*resource;
 
-- 
2.20.1


WARNING: multiple messages have this Message-ID (diff)
From: Ulf Hansson <ulf.hansson@linaro.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	linux-kernel@vger.kernel.org
Cc: Ulf Hansson <ulf.hansson@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Linus Walleij <linus.walleij@linaro.org>,
	Russell King <linux@armlinux.org.uk>,
	Haibo Chen <haibo.chen@nxp.com>, Vinod Koul <vkoul@kernel.org>,
	linux-arm-kernel@lists.infradead.org, dmaengine@vger.kernel.org,
	stable@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Ludovic Barre <ludovic.barre@st.com>
Subject: [PATCH 1/2] driver core: platform: Initialize dma_parms for platform devices
Date: Wed, 25 Mar 2020 12:34:06 +0100	[thread overview]
Message-ID: <20200325113407.26996-2-ulf.hansson@linaro.org> (raw)
In-Reply-To: <20200325113407.26996-1-ulf.hansson@linaro.org>

It's currently the platform driver's responsibility to initialize the
pointer, dma_parms, for its corresponding struct device. The benefit with
this approach allows us to avoid the initialization and to not waste memory
for the struct device_dma_parameters, as this can be decided on a case by
case basis.

However, it has turned out that this approach is not very practical.  Not
only does it lead to open coding, but also to real errors. In principle
callers of dma_set_max_seg_size() doesn't check the error code, but just
assumes it succeeds.

For these reasons, let's do the initialization from the common platform bus
at the device registration point. This also follows the way the PCI devices
are being managed, see pci_device_add().

Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/base/platform.c         | 1 +
 include/linux/platform_device.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index b5ce7b085795..46abbfb52655 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -512,6 +512,7 @@ int platform_device_add(struct platform_device *pdev)
 		pdev->dev.parent = &platform_bus;
 
 	pdev->dev.bus = &platform_bus_type;
+	pdev->dev.dma_parms = &pdev->dma_parms;
 
 	switch (pdev->id) {
 	default:
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 041bfa412aa0..81900b3cbe37 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -25,6 +25,7 @@ struct platform_device {
 	bool		id_auto;
 	struct device	dev;
 	u64		platform_dma_mask;
+	struct device_dma_parameters dma_parms;
 	u32		num_resources;
 	struct resource	*resource;
 
-- 
2.20.1


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2020-03-25 11:34 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25 11:34 [PATCH 0/2] amba/platform: Initialize dma_parms at the bus level Ulf Hansson
2020-03-25 11:34 ` Ulf Hansson
2020-03-25 11:34 ` Ulf Hansson [this message]
2020-03-25 11:34   ` [PATCH 1/2] driver core: platform: Initialize dma_parms for platform devices Ulf Hansson
2020-03-25 15:23   ` Ludovic BARRE
2020-03-25 15:23     ` Ludovic BARRE
2020-03-26 11:01   ` Linus Walleij
2020-03-26 11:01     ` Linus Walleij
2020-03-26 11:06   ` Arnd Bergmann
2020-03-26 11:06     ` Arnd Bergmann
2020-03-27 15:03   ` Sasha Levin
2020-03-25 11:34 ` [PATCH 2/2] amba: Initialize dma_parms for amba devices Ulf Hansson
2020-03-25 11:34   ` Ulf Hansson
2020-03-25 15:24   ` Ludovic BARRE
2020-03-25 15:24     ` Ludovic BARRE
2020-03-26 11:02   ` Linus Walleij
2020-03-26 11:02     ` Linus Walleij
2020-03-26 11:07   ` Arnd Bergmann
2020-03-26 11:07     ` Arnd Bergmann
2020-03-26  4:41 ` [PATCH 0/2] amba/platform: Initialize dma_parms at the bus level BOUGH CHEN
2020-03-26  4:41   ` BOUGH CHEN
2020-03-27  3:02   ` BOUGH CHEN
2020-03-27  3:02     ` BOUGH CHEN
2020-03-27 15:34     ` Ulf Hansson
2020-03-27 15:34       ` Ulf Hansson
2020-03-27 19:15       ` Robin Murphy
2020-03-27 19:15         ` Robin Murphy
2020-03-31 18:08         ` Ulf Hansson
2020-03-31 18:08           ` Ulf Hansson

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