Re: [PATCH v4 2/3] usb: dwc3: fix dcache flush range calculation

[Marek Vasut <marex@denx.de>]

On 10/11/24 4:38 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 CACHELINE_SIZE.
> 
> 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@baylibre.com>
> Signed-off-by: Neil Armstrong <neil.armstrong@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..0ede323671b 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 & ~(CACHELINE_SIZE - 1);
> +	uintptr_t end_addr = ALIGN((uintptr_t)addr + length, CACHELINE_SIZE);
> +
> +	flush_dcache_range((unsigned long)start_addr, (unsigned long)end_addr);
>   }
>   #endif /* __DRIVERS_USB_DWC3_IO_H */

You likely want a max(CONFIG_SYS_CACHELINE_SIZE, 
dwc3-buffer-alignment-requirement) to really correctly align the buffer.