diff mbox series

[2/2] amba: Initialize dma_parms for amba devices

Message ID 20200325113407.26996-3-ulf.hansson@linaro.org (mailing list archive)
State Mainlined
Commit 5caf6102e32ead7ed5d21b5309c1a4a7d70e6a9f
Headers show
Series amba/platform: Initialize dma_parms at the bus level | expand

Commit Message

Ulf Hansson March 25, 2020, 11:34 a.m. UTC
It's currently the amba 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 amba 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: Russell King <linux@armlinux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/amba/bus.c       | 2 ++
 include/linux/amba/bus.h | 1 +
 2 files changed, 3 insertions(+)

Comments

Ludovic BARRE March 25, 2020, 3:24 p.m. UTC | #1
Le 3/25/20 à 12:34 PM, Ulf Hansson a écrit :
> It's currently the amba 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 amba bus at
> the device registration point. This also follows the way the PCI devices
> are being managed, see pci_device_add().
> 

tested with mmc: mmci_sdmmc fix
Tested-by: Ludovic Barre <ludovic.barre@st.com>

> Suggested-by: Christoph Hellwig <hch@lst.de>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>   drivers/amba/bus.c       | 2 ++
>   include/linux/amba/bus.h | 1 +
>   2 files changed, 3 insertions(+)
> 
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index fe1523664816..5e61783ce92d 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -374,6 +374,8 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
>   	WARN_ON(dev->irq[0] == (unsigned int)-1);
>   	WARN_ON(dev->irq[1] == (unsigned int)-1);
>   
> +	dev->dev.dma_parms = &dev->dma_parms;
> +
>   	ret = request_resource(parent, &dev->res);
>   	if (ret)
>   		goto err_out;
> diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h
> index 26f0ecf401ea..0bbfd647f5c6 100644
> --- a/include/linux/amba/bus.h
> +++ b/include/linux/amba/bus.h
> @@ -65,6 +65,7 @@ struct amba_device {
>   	struct device		dev;
>   	struct resource		res;
>   	struct clk		*pclk;
> +	struct device_dma_parameters dma_parms;
>   	unsigned int		periphid;
>   	unsigned int		cid;
>   	struct amba_cs_uci_id	uci;
>
Linus Walleij March 26, 2020, 11:02 a.m. UTC | #2
On Wed, Mar 25, 2020 at 12:34 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:

> It's currently the amba 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 amba 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: Russell King <linux@armlinux.org.uk>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij
Arnd Bergmann March 26, 2020, 11:07 a.m. UTC | #3
On Wed, Mar 25, 2020 at 12:34 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> It's currently the amba 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 amba 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: Russell King <linux@armlinux.org.uk>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Acked-by: Arnd Bergmann <arnd@arndb.de>
diff mbox series

Patch

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index fe1523664816..5e61783ce92d 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -374,6 +374,8 @@  static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
 	WARN_ON(dev->irq[0] == (unsigned int)-1);
 	WARN_ON(dev->irq[1] == (unsigned int)-1);
 
+	dev->dev.dma_parms = &dev->dma_parms;
+
 	ret = request_resource(parent, &dev->res);
 	if (ret)
 		goto err_out;
diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h
index 26f0ecf401ea..0bbfd647f5c6 100644
--- a/include/linux/amba/bus.h
+++ b/include/linux/amba/bus.h
@@ -65,6 +65,7 @@  struct amba_device {
 	struct device		dev;
 	struct resource		res;
 	struct clk		*pclk;
+	struct device_dma_parameters dma_parms;
 	unsigned int		periphid;
 	unsigned int		cid;
 	struct amba_cs_uci_id	uci;