Hi Miquel,
On 09.08.2018 10:13, Miquel Raynal wrote:
Stefan Roese sr@denx.de wrote on Thu, 9 Aug 2018 07:24:14 +0200:
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?
Actually I'm fine with it as SPI-mem only uses half-duplex. It's not necessary to limit its use to SPI controllers (drivers) supporting full-duplex.
Stefan, shall I fold your changes in my series and resend? Or do I resend only my original patches and Jagan/Tom will apply yours on top of it?
Do you need to re-send your original patches? If yes, then please do with my patches folded in. If a re-send is not necessary, then Jagan or Tom should be able to apply your latest patchset and mine on top of it.
Thanks, Stefan