[PATCH v2 2/3] usb: dwc3: fix dcache flush range calculation

[Neil Armstrong]

On 01/10/2024 17:21, Marek Vasut wrote:
> On 7/24/24 5:48 PM, Neil Armstrong wrote:
>> The current flush operation will omit doing a flush/invalidate on
>> the first and last bytes if the base address and size are not aligned
>> with DMA_MINALIGN.
>>
>> This causes operation failures Qualcomm platforms.
>>
>> Take in account the alignment and size of the buffer and also
>> flush the previous and last cacheline.
>>
>> Reviewed-by: Mattijs Korpershoek <mkorpershoek at baylibre.com>
>> Signed-off-by: Neil Armstrong <neil.armstrong at linaro.org>
>> ---
>>   drivers/usb/dwc3/io.h | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/dwc3/io.h b/drivers/usb/dwc3/io.h
>> index 04791d4c9be..1aaf5413c6d 100644
>> --- a/drivers/usb/dwc3/io.h
>> +++ b/drivers/usb/dwc3/io.h
>> @@ -50,6 +50,9 @@ static inline void dwc3_writel(void __iomem *base, u32 offset, u32 value)
>>   static inline void dwc3_flush_cache(uintptr_t addr, int length)
>>   {
>> -    flush_dcache_range(addr, addr + ROUND(length, CACHELINE_SIZE));
>> +    uintptr_t start_addr = (uintptr_t)addr & ~(ARCH_DMA_MINALIGN - 1);
>> +    uintptr_t end_addr = ALIGN((uintptr_t)addr + length, ARCH_DMA_MINALIGN);
>> +
>> +    flush_dcache_range(start_addr, end_addr);
> include/cpu_func.h:void flush_dcache_range(unsigned long start, unsigned long stop);
> 
> So you shouldn't be feeding this function uintptr_t , right ?

uintptr_t is the right type to perform pointer calculation,
I should probably cast it to unsigned long for flush_dcache_range.

I'll do this in v2.

> 
> Also, why change CACHELINE_SIZE to ARCH_DMA_MINALIGN ?

Because all the memory allocated for DMA was done with dma_alloc_coherent()
which uses ARCH_DMA_MINALIGN directly or indirectly.

I should probably remove CACHELINE_SIZE in the same patch.

Thanks,
Neil