Re: [PATCH 1/2] HID: intel-ish-hid: fix cache management mistake

[Arnd Bergmann]

On Wed, May 29, 2024, at 08:46, Zhang, Lixu wrote:
>>
>>-#include <linux/cacheflush.h>
>> #include <linux/container_of.h>
>> #include <linux/dev_printk.h>
>> #include <linux/dma-mapping.h>
>>@@ -175,10 +174,11 @@ static int prepare_dma_bufs(struct ishtp_device
>>*dev,
>> 			return -ENOMEM;
>>
>> 		fragment->fragment_tbl[i].ddr_adrs =
>>cpu_to_le64(dma_addr);
>>+
>>+		memcpy(dma_bufs[i], ish_fw->data + offset, fragment-
>>>fragment_tbl[i].length);
> fragment->fragment_tbl[i].length was used before assignment.
> 
>>+		dma_wmb();
> I tested it on the platform, but it didn't wok.
>

What behavior do you see instead? If the manual cache
flush works around a bug, that would indicate that the
device itself is not coherent and the dma_alloc_coherent()
in the architecture is broken.

     Arnd