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SubjectRe: [PATCH v2 22/27] thunderbolt: Add support for DMA configuration based mailbox
On Fri, May 26, 2017 at 7:09 PM, Mika Westerberg
<mika.westerberg@linux.intel.com> 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

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