lkml.org 
[lkml]   [2017]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 13/31] nds32: DMA mapping API
2017-11-08 17:09 GMT+08:00 Arnd Bergmann <arnd@arndb.de>:
> On Wed, Nov 8, 2017 at 6:55 AM, Greentime Hu <green.hu@gmail.com> wrote:
>
>> +static void consistent_sync(void *vaddr, size_t size, int direction)
>> +{
>> + unsigned long start = (unsigned long)vaddr;
>> + unsigned long end = start + size;
>> +
>> + switch (direction) {
>> + case DMA_FROM_DEVICE: /* invalidate only */
>> + cpu_dma_inval_range(start, end);
>> + break;
>> + case DMA_TO_DEVICE: /* writeback only */
>> + cpu_dma_wb_range(start, end);
>> + break;
>> + case DMA_BIDIRECTIONAL: /* writeback and invalidate */
>> + cpu_dma_wbinval_range(start, end);
>> + break;
>> + default:
>> + BUG();
>> + }
>> +}
>
>> +
>> +static void
>> +nds32_dma_sync_single_for_cpu(struct device *dev, dma_addr_t handle,
>> + size_t size, enum dma_data_direction dir)
>> +{
>> + consistent_sync((void *)dma_to_virt(dev, handle), size, dir);
>> +}
>> +
>> +static void
>> +nds32_dma_sync_single_for_device(struct device *dev, dma_addr_t handle,
>> + size_t size, enum dma_data_direction dir)
>> +{
>> + consistent_sync((void *)dma_to_virt(dev, handle), size, dir);
>> +}
>
> You do the same cache operations for _to_cpu and _to_device, which
> usually works,
> but is more expensive than you need. It's better to take the ownership into
> account and only do what you need.
>

Thanks.

Like this?

static void
nds32_dma_sync_single_for_cpu(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
consistent_sync((void *)dma_to_virt(dev, handle), size,
DMA_FROM_DEVICE);
}

static void
nds32_dma_sync_single_for_device(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
consistent_sync((void *)dma_to_virt(dev, handle), size,
DMA_TO_DEVICE);
}

\
 
 \ /
  Last update: 2017-11-09 08:13    [W:0.318 / U:0.504 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site