lkml.org 
[lkml]   [2016]   [Aug]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v5] spi: spi-ti-qspi: Add DMA support for QSPI mmap read
On Tue, Aug 09, 2016 at 04:33:11PM +0530, Vignesh R wrote:

> +static int ti_qspi_map_buf(struct ti_qspi *qspi, void *buf,
> + unsigned int len, struct sg_table *sgt)
> +{
> + unsigned int max_seg_size =
> + dma_get_max_seg_size(qspi->rx_chan->device->dev);
> + unsigned int desc_len = min_t(int, max_seg_size, PAGE_SIZE);
> + int sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
> + struct page *vm_page;
> + size_t min;
> + int i, ret;
> +
> + ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
> + if (ret)
> + return ret;
> +
> + for (i = 0; i < sgs; i++) {
> + min = min_t(size_t, len, desc_len -
> + offset_in_page(buf));
> + vm_page = kmap_to_page(buf);
> + if (!vm_page) {
> + sg_free_table(sgt);
> + return -ENOMEM;
> + }
> + sg_set_page(&sgt->sgl[i], vm_page, min,
> + offset_in_page(buf));
> + buf += min;
> + len -= min;

This looks a lot like the core code for mapping the buffers - why is
this open coded rather than reused?
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2016-08-09 14:21    [W:0.069 / U:0.212 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site