Re: [PATCH v2 22/27] thunderbolt: Add support for DMA configuration based mailbox

[Andy Shevchenko]

On Fri, May 26, 2017 at 7:09 PM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> The DMA (NHI) port of a switch provides access to the NVM of the host
> controller (and devices starting from Intel Alpine Ridge). The NVM
> contains also more complete DROM for the root switch including vendor
> and device identification strings.

> +               ret = dma_port_flash_read_block(dma, address, dma->buf,
> +                                               ALIGN(nbytes, 4));
> +               if (ret) {
> +                       if (ret == -ETIMEDOUT) {
> +                               if (retries--)
> +                                       continue;
> +                               ret = -EIO;
> +                       }
> +                       return ret;
> +               }
> +
> +               memcpy(buf, dma->buf + offset, nbytes);

> +       do {
> +               u32 nbytes = min_t(u32, size, MAIL_DATA_DWORDS * 4);
> +               int ret;
> +
> +               memcpy(dma->buf + offset, buf, nbytes);
> +
> +               ret = dma_port_flash_write_block(dma, address, buf, nbytes);
> +               if (ret) {
> +                       if (ret == -ETIMEDOUT) {
> +                               if (retries--)
> +                                       continue;
> +                               ret = -EIO;
> +                       }
> +                       return ret;
> +               }

Just to be sure I didn't miss anything.
Can't we just map buffer into DMA capable address space instead of memcpy()'ing?

-- 
With Best Regards,
Andy Shevchenko