Messages in this thread | | | Date | Wed, 17 Apr 2024 12:50:48 +0200 | Subject | Re: [PATCH 11/15] tty: msm_serial: use dmaengine_prep_slave_sg() | From | Jiri Slaby <> |
| |
On 17. 04. 24, 12:15, Marek Szyprowski wrote: > Hi Jiri, > > On 16.04.2024 12:23, Jiri Slaby wrote: >> 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@kernel.org> >>>> Cc: Bjorn Andersson <andersson@kernel.org> >>>> Cc: Konrad Dybcio <konrad.dybcio@linaro.org> >>>> Cc: linux-arm-msm@vger.kernel.org >>> >>> 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… > > I've spent some time digging into this issue and frankly speaking I > still have no idea WHY it doesn't work (or I seriously mixed something > in the scatterlist principles). However I found a workaround to make it > working. Maybe it will help a bit guessing what happens there. .. > @@ -434,7 +436,7 @@ static void msm_start_tx(struct uart_port *port) > struct msm_dma *dma = &msm_port->tx_dma; > > /* Already started in DMA mode */ > - if (sg_dma_len(&dma->tx_sg)) > + if (dma->mapped)
Thanks for looking into this.
I was hesitant if I should use a flag. I should have, apparently.
Quick question: What's value of CONFIG_NEED_SG_DMA_LENGTH in your .config?
thanks, -- js suse labs
| |