linux-kernel - Re: [PATCH] arm64: Implement arch_setup_pdev

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Message-ID: <CAMz4kuJbqdmO=Uk07kWSnpg0+yGkzsZMWwNZdyMPH_-7svDdnQ@mail.gmail.com>
Date:	Tue, 7 Jun 2016 17:22:25 +0800
From:	Baolin Wang <baolin.wang@...aro.org>
To:	Robin Murphy <robin.murphy@....com>
Cc:	catalin.marinas@....com, will.deacon@....com, jroedel@...e.de,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jisheng Zhang <jszhang@...vell.com>,
	Suravee.Suthikulpanit@....com, Arnd Bergmann <arnd@...db.de>,
	linux-arm-kernel@...ts.infradead.org,
	LKML <linux-kernel@...r.kernel.org>,
	Mark Brown <broonie@...nel.org>,
	Felipe Balbi <balbi@...nel.org>
Subject: Re: [PATCH] arm64: Implement arch_setup_pdev_archdata hook

On 7 June 2016 at 17:15, Robin Murphy <robin.murphy@....com> wrote:
> On 07/06/16 09:29, Baolin Wang wrote:
>>
>> Now on ARM64 platform, it will set 'dummy_dma_ops' for device dma_ops if
>> it did not call 'arch_setup_dma_ops' at device creation time by issuing
>> platform_device_alloc() function, that will cause failure when setting
>> the dma mask for device.
>
>
> Yes, that's rather the whole point. DMA-capable devices are real hardware,
> therefore don't spring out of thin air without being described in DT or
> ACPI.

OK.

>
> Please elaborate on the situation that you're attempting to address here
> (please don't let it be the ongoing Designware USB catastrophe ;))

Yes, like you mentioned, we met problems at DesignWare USB3 controller
host glue, do you have any better solutions to solve this problem?
Thanks.

>
> Robin.
>
>
>> Hence We need to hook the archdata to setup proper dma_ops for these
>> devices.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>> ---
>>   arch/arm64/mm/dma-mapping.c |   21 +++++++++++++++++++++
>>   1 file changed, 21 insertions(+)
>>
>> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
>> index c566ec8..04e057b 100644
>> --- a/arch/arm64/mm/dma-mapping.c
>> +++ b/arch/arm64/mm/dma-mapping.c
>> @@ -26,6 +26,7 @@
>>   #include <linux/dma-contiguous.h>
>>   #include <linux/vmalloc.h>
>>   #include <linux/swiotlb.h>
>> +#include <linux/platform_device.h>
>>
>>   #include <asm/cacheflush.h>
>>
>> @@ -961,3 +962,23 @@ void arch_setup_dma_ops(struct device *dev, u64
>> dma_base, u64 size,
>>         dev->archdata.dma_coherent = coherent;
>>         __iommu_setup_dma_ops(dev, dma_base, size, iommu);
>>   }
>> +
>> +void arch_setup_pdev_archdata(struct platform_device *pdev)
>> +{
>> +       if (!pdev->dev.archdata.dma_ops)
>> +               pdev->dev.archdata.dma_ops = &swiotlb_dma_ops;
>> +
>> +       /*
>> +        * Set default coherent_dma_mask to 32 bit. Drivers are expected
>> to
>> +        * setup the correct supported mask.
>> +        */
>> +       if (!pdev->dev.coherent_dma_mask)
>> +               pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
>> +
>> +       /*
>> +        * Set it to coherent_dma_mask by default if the architecture
>> +        * code has not set it.
>> +        */
>> +       if (!pdev->dev.dma_mask)
>> +               pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
>> +}
>>
>



-- 
Baolin.wang
Best Regards