[v1,2/2] spi: pxa2xx: Update DMA mapping and using logic in the documentation
Commit Message
Update DMA mapping and using logic in the documentation to follow what
the code does.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
Documentation/spi/pxa2xx.rst | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
Comments
On Fri, Dec 08, 2023 at 12:13:40AM +0200, Andy Shevchenko wrote:
> Update DMA mapping and using logic in the documentation to follow what
> the code does.
...
> - if !enable_dma then
> - always use PIO transfers
> + if spi_message.len > 65536 then
> + if spi_message.is_dma_mapped or rx_dma_buf != 0 or tx_dma_buf != 0 then
> + reject premapped transfers
Here seems inconsistent indentation. I'll fix it in the next version.
Mark, should I resend patch 1 as well?
On Fri, Dec 08, 2023 at 06:12:05PM +0200, Andy Shevchenko wrote:
> Here seems inconsistent indentation. I'll fix it in the next version.
> Mark, should I resend patch 1 as well?
Yes, please.
@@ -193,17 +193,14 @@ mode supports both coherent and stream based DMA mappings.
The following logic is used to determine the type of I/O to be used on
a per "spi_transfer" basis::
- if !enable_dma then
- always use PIO transfers
+ if spi_message.len > 65536 then
+ if spi_message.is_dma_mapped or rx_dma_buf != 0 or tx_dma_buf != 0 then
+ reject premapped transfers
- if spi_message.len > 8191 then
print "rate limited" warning
use PIO transfers
- if spi_message.is_dma_mapped and rx_dma_buf != 0 and tx_dma_buf != 0 then
- use coherent DMA mode
-
- if rx_buf and tx_buf are aligned on 8 byte boundary then
+ if enable_dma and the size is in the range [DMA burst size..65536] then
use streaming DMA mode
otherwise