On Saturday 04 July 2015 06:23 PM, R, Vignesh wrote:
On 7/3/2015 5:12 PM, Tom Rini wrote:
On Fri, Jul 03, 2015 at 04:46:10PM +0530, Vignesh R wrote:
ti_qspi uses memory map mode for faster read. Enabling DMA will increase read speed by 3x @48MHz on DRA74 EVM.
Signed-off-by: Vignesh R vigneshr@ti.com
This ignores the feedback from http://lists.denx.de/pipermail/u-boot/2014-July/183715.html where we need to model the DMA changes on how it's done for mxs_spi.c
Sorry.. I didn't look into that before. mxs_spi uses peripheral DMA to read/write flash. But ti_qspi can use DMA to read from flash in mmap mode only. In current u-boot, defining CONFIG_TI_SPI_MMAP will make memory map address available (spi_flash->memory_map) to sf layer and spi_flash_cmd_read_ops() (in sf_ops.c) directly calls memcpy() to read data from flash into buffer. There is no spi_xfer() call to the ti_qspi driver at all.
In order to implement mxs_spi like approach for ti_qspi.c, I can delete mmap handling in sf_ops.c( I don't think any other spi driver uses this part of code), so that spi_xfer() is always called. And then, in spi_xfer() implementation of ti_qspi, I can do DMA transfer similar to mxs_spi.c. Is this approach ok?
I think I misinterpreted the thread previously. The suggestion is to move DMA initialization related code from to ti-edma3.c and use spi_flash_copy_mmap() just to pass addresses to ti-edma3 apis. Am I correct?