Re: [PATCH 11/15] tty: msm_serial: use dmaengine_prep_slave_sg()

From: Jiri Slaby
Date: Tue Apr 16 2024 - 06:23:29 EST


On 15. 04. 24, 23:17, Marek Szyprowski wrote:
On 05.04.2024 08:08, Jiri Slaby (SUSE) wrote:
This is a preparatory for the serial-to-kfifo switch. kfifo understands
only scatter-gatter approach, so switch to that.

No functional change intended, it's just dmaengine_prep_slave_single()
inline expanded.

And in this case, switch from dma_map_single() to dma_map_sg() too. This
needs struct msm_dma changes. I split the rx and tx parts into an union.
TX is now struct scatterlist, RX remains the old good phys-virt-count
triple.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
Cc: Bjorn Andersson <andersson@xxxxxxxxxx>
Cc: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
Cc: linux-arm-msm@xxxxxxxxxxxxxxx

I've just found that this patch broke UART operation on DragonBoard
410c. I briefly checked and didn't notice anything obviously wrong here,
but the board stops transmitting any data from its serial port after the
first message. I will try to analyze this issue a bit more tomorrow.

I double checked, but I see no immediate issues in the patch too. So please, if you can analyze this more…

thanks,
--
js
suse labs