On 17. 04. 24, 14:45, Marek Szyprowski wrote:
On 17.04.2024 12:50, Jiri Slaby wrote:
On 17. 04. 24, 12:15, Marek Szyprowski wrote:
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@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…
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?
CONFIG_NEED_SG_DMA_LENGTH=y
I alse tried to change the "if (dma->mapped)" check in msm_start_tx() to:
1. if (dma->tx_sg.length)
2. if (dma->tx_sg.page_link & ~SG_PAGE_LINK_MASK)
but none of the above worked what is really strange and incomprehensible
for me.
Thanks. Neither for me. Could you add:
{
static DEFINE_RATELIMIT_STATE(rs,
DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
if (dma->mapped != !!sg_dma_len(&dma->tx_sg) &&
__ratelimit(&rs))
printk_deferred(KERN_DEBUG "%s (%d): mapped=%u
dma_len=%u\n",
__func__, __LINE__,
dma->mapped, sg_dma_len(&dma->tx_sg));
}
before each of your 'if (dma->mapped)' to see where sg_dma_len() is
wrong and what is its value in the bad case. I hope I did the logic right.
thanks,
--
js
suse labs
