linux-kernel - Re: [PATCH] usb: chipidea: Configure DMA properties and ops from DT

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Date:	Mon, 22 Feb 2016 10:03:21 +0000
From:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:	Bjorn Andersson <bjorn.andersson@...aro.org>,
	Peter Chen <Peter.Chen@....com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-usb@...r.kernel.org,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: chipidea: Configure DMA properties and ops from DT



On 22/02/16 05:32, Bjorn Andersson wrote:
> On certain platforms (e.g. ARM64) the dma_ops needs to be explicitly set
> to be able to do DMA allocations, so use the of_dma_configure() helper
> to populate the dma properties and assign an appropriate dma_ops.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>   drivers/usb/chipidea/core.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
> index 7404064b9bbc..047b9d4e67aa 100644
> --- a/drivers/usb/chipidea/core.c
> +++ b/drivers/usb/chipidea/core.c
> @@ -62,6 +62,7 @@
>   #include <linux/usb/chipidea.h>
>   #include <linux/usb/of.h>
>   #include <linux/of.h>
> +#include <linux/of_device.h>
>   #include <linux/phy.h>
>   #include <linux/regulator/consumer.h>
>   #include <linux/usb/ehci_def.h>
> @@ -834,6 +835,9 @@ struct platform_device *ci_hdrc_add_device(struct device *dev,
>   	pdev->dev.dma_parms = dev->dma_parms;
>   	dma_set_coherent_mask(&pdev->dev, dev->coherent_dma_mask);
>
> +	if (IS_ENABLED(CONFIG_OF) && dev->of_node)
> +		of_dma_configure(&pdev->dev, dev->of_node);
> +
Would we hit the same issue if we are on non Device tree platforms like 
ACPI or platform device style itself?


>   	ret = platform_device_add_resources(pdev, res, nres);
>   	if (ret)
>   		goto err;
>

I think this is the side effect of commit 
1dccb598df549d892b6450c261da54cdd7af44b4(arm64: simplify dma_get_ops)

None of the drivers call of_dma_configure() explicitly, which makes me 
feel that we are doing something wrong. TBH, this should be handled in 
more generic way rather than driver like this having an explicit call to 
of_dma_configure().


On the other hand, I think we could also solve the issue by using 
correct device(parent device) while allocating dma/dma-pool.


------------------------>cut<-----------------------------

diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index 6e53c24..0293ed5 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -1844,13 +1844,13 @@ static int udc_start(struct ci_hdrc *ci)
         INIT_LIST_HEAD(&ci->gadget.ep_list);

         /* alloc resources */
-       ci->qh_pool = dma_pool_create("ci_hw_qh", dev,
+       ci->qh_pool = dma_pool_create("ci_hw_qh", dev->parent,
                                        sizeof(struct ci_hw_qh),
                                        64, CI_HDRC_PAGE_SIZE);
         if (ci->qh_pool == NULL)
                 return -ENOMEM;

-       ci->td_pool = dma_pool_create("ci_hw_td", dev,
+       ci->td_pool = dma_pool_create("ci_hw_td", dev->parent,
                                        sizeof(struct ci_hw_td),
                                        64, CI_HDRC_PAGE_SIZE);
         if (ci->td_pool == NULL) {
------------------------>cut<-----------------------------


--srini