[ + Greg Kroah-Hartman ]
On 01/10/2015 10:55, Andy Shevchenko wrote:
On Wed, 2015-09-30 at 16:11 -0400, Peter Hurley wrote:
[ + Heikko ]
On 09/30/2015 10:12 AM, Andy Shevchenko wrote:
On Wed, 2015-09-30 at 09:52 -0400, Peter Hurley wrote:
[ + Andy Shevchenko ]
On 09/30/2015 08:46 AM, Frederic Danis wrote:
This reverts commit 9119fba0cfeda6d415c9f068df66838a104b87cb.
Hi Frederic,
It's customary to mail the commit author in patches which revert
their work.
This commit prevents from sending "big" file using Bluetooth.
When sending a lot of data quickly through the Bluetooth
interface,
and
after a variable amount of data sent, transfer fails with
error:
kernel: [ 415.247453] Bluetooth: hci0 hardware error 0x00
Frederic, I forgot to ask how exactly the hw setup looks like?
The message above is not present in the kernel (the closest what I
found is
drivers/bluetooth/btintel.c:98: BT_ERR("%s: Hardware error 0x%2.2x",
hdev->name, code);
which makes me think you have USB BT adapter attached to the same
machine. Am I wrong?
Hmmm, was there any other information regarding why this
happened?
Frederic informed us privately about this issue.
Ok, except no one else knows that.
Least of all Greg, since the revert wasn't even addressed to him
either :/
Agree, it's better to inform all parties about the problem.
I tried to hunt the
root cause but mostly (there was one observation but apparently
seems
it is not related to this issue) nothing looks wrong.
Eg., did the driver mistakenly re-order i/o (DMA occurred after
PIO)?
I have few tracing dumps which Frederic provides to me, but I
couldn't
see such a problem. Maybe I missed it.
Ok.
My commit 9119fba0cfed introduces interleaved IO (DMA/PIO) which
makes
it like DMA -> PIO -> DMA -> ...
I realize that. However interleaving DMA and PIO _must_ be supported
by the platform to enable DMA for 8250 serial devices anway.
When Heikki added DMA support to the 8250 driver, he left out
important
functionality which requires interleaved DMA and PIO.
When I fix that omission, platforms using DMA that shouldn't be are
going
to get broken anyway.
Regards,
Peter Hurley
Or, might there be some race condition in the dmaengine driver on
this
platform?
There is [1] might be a clue, though I don't think it's directly
related.
[1] http://www.spinics.net/lists/linux-spi/msg01151.html
The change prevents interleaved DMA/PIO IO.
Regards,
Peter Hurley
Found on T100TA.
After reverting this commit, send works fine for any file size.
Signed-off-by: Frederic Danis <frederic.danis@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_dma.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_dma.c
b/drivers/tty/serial/8250/8250_dma.c
index 21d01a4..e508939 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -80,10 +80,6 @@ int serial8250_tx_dma(struct uart_8250_port
*p)
return 0;
dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail,
UART_XMIT_SIZE);
- if (dma->tx_size < p->port.fifosize) {
- ret = -EINVAL;
- goto err;
- }
desc = dmaengine_prep_slave_single(dma->txchan,
dma->tx_addr + xmit
->tail,
--
Frederic Danis Open Source Technology Center
frederic.danis@xxxxxxxxx Intel Corporation
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