Hi Miquel,
On 08.08.2018 10:56, Miquel Raynal wrote:
Boris Brezillon boris.brezillon@bootlin.com wrote on Tue, 7 Aug 2018 15:28:02 +0200:
On Tue, 7 Aug 2018 14:16:52 +0200 Stefan Roese sr@denx.de wrote:
Some SPI controller do not support full-duplex SPI transfers. This patch changes the SPI transfer into 2 separate transfers - or 1, if no data is to transmitted.
With this change, no buffers need to be allocated anymore. We use the TX and RX buffers that are passed to spi_mem_exec_op() directly.
Signed-off-by: Stefan Roese sr@denx.de Suggested-by: Boris Brezillon boris.brezillon@bootlin.com Cc: Miquel Raynal miquel.raynal@bootlin.com Cc: Boris Brezillon boris.brezillon@bootlin.com Cc: Jagan Teki jagan@openedev.com
Looks good overall, just a few comments (that you might chose to ignore if you disagree).
Reviewed-by: Boris Brezillon boris.brezillon@bootlin.com
Sorry for being a bit late on the discussion, but while I do agree with the change, I'm not sure about its implementation : I think SPI controllers are supposed to be abstracted by the SPI layer. Addressing the controller's limitations in the SPI-mem layer would not be appropriate.
Would it be possible to adapt spi_xfer() to handle such case?
No, I don't think so. Its impossible to guess in the SPI driver layer, which parts of the message are TX data and which are RX data. So this message can't be split up into a half-duplex one here. This can only be done in the driver which constructs the SPI messages.
Or did I miss something here?
Thanks, Stefan