Hi,
(please don't top-post)
"Thang Q. Nguyen" <tqnguyen@xxxxxxx> writes:
> Hi Balbi,
> If CONFIG_DMA_CMA=y, dma mask is set properly. The issue just happen
> when CONFIG_DMA_CMA is not set. In this case, dma mask is not set and
> we need this code to check if dma mask should be manually set to 32 or
> 64.
Can you point me to the code which has this conditional ? Why would
DMA_CMA=n mean that dma_mask isn't initialized ? According to DMA_CMA's
help text (see below) that's supposed to allow drivers to *allocate*
large contiguous buffers, but that's not the case here.
config DMA_CMA
bool "DMA Contiguous Memory Allocator"
depends on HAVE_DMA_CONTIGUOUS && CMA
help
This enables the Contiguous Memory Allocator which allows drivers
to allocate big physically-contiguous blocks of memory for use with
hardware components that do not support I/O map nor scatter-gather.
You can disable CMA by specifying "cma=0" on the kernel's command
line.
For more information see <include/linux/dma-contiguous.h>.
If unsure, say "n".
>
> ----
> Thang
>
> On Wed, Mar 30, 2016 at 8:09 PM, Felipe Balbi
> <felipe.balbi@xxxxxxxxxxxxxxx> wrote:
>>
>> Hi,
>>
>> "Thang Q. Nguyen" <tqnguyen@xxxxxxx> writes:
>>> From: "Thang Q. Nguyen" <tqnguyen@xxxxxxx>
>>>
>>> Add 64-bit DMA operation support to the USB DWC3 driver.
>>> First attempt to set the coherent DMA mask for 64-bit DMA.
>>> If that failed, attempt again with 32-bit DMA.
>>>
>>> Changes from v2:
>>> - None.
>>>
>>> Changes from v1:
>>> - Remove WARN_ON if dma_mask is NULL
>>
>> these changes lines should be between the tearline (---) and diffstat
>> below.
>>
>>> Signed-off-by: Thang Q. Nguyen <tqnguyen@xxxxxxx>
>>> ---
>>> drivers/usb/dwc3/core.c | 15 +++++++++++++++
>>> 1 file changed, 15 insertions(+)
>>>
>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>> index de5e01f..2479c24 100644
>>> --- a/drivers/usb/dwc3/core.c
>>> +++ b/drivers/usb/dwc3/core.c
>>> @@ -831,6 +831,21 @@ static int dwc3_probe(struct platform_device *pdev)
>>> dwc->mem = mem;
>>> dwc->dev = dev;
>>>
>>> + /* Try to set 64-bit DMA first */
>>> + if (!pdev->dev.dma_mask)
>>> + /* Platform did not initialize dma_mask */
>>> + ret = dma_coerce_mask_and_coherent(&pdev->dev,
>>> + DMA_BIT_MASK(64));
>>> + else
>>> + ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
>>> +
>>> + /* If seting 64-bit DMA mask fails, fall back to 32-bit DMA mask */
>>> + if (ret) {
>>> + ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
>>> + if (ret)
>>> + return ret;
>>> + }
>>
>> Also, why is it so that you need this now ? glue layers are copying dma
>> mask from parent device and that should be set properly. This really
>> shouldn't be necessary in dwc3-core; it would mean that glue layer
>> didn't set this device up properly.
>>
>> --
>> balbi
>
>
>
> --
>
> Thang Q. Nguyen | Staff SW Eng.
>
> C: +849.7684.7606 | O: +848.3770.0640
>
> F: +848.3770.0641 | tqnguyen@xxxxxxx
--
balbi
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