From: jiri.prchal@aksignal•cz (Jiří Prchal)
To: linux-arm-kernel@lists•infradead.org
Subject: [BUG] at91: serial: is it using DMA?
Date: Wed, 20 May 2015 15:26:17 +0200 [thread overview]
Message-ID: <555C8B79.4030900@aksignal.cz> (raw)
Hi all,
I discovered problem with serial driver in kernel 4.0.4 on at91sam9g25 at 400MHz.
When I want receive frames on UART at 115200kb/s I get many errors caused by loss of some bytes.
These errors were there if no DMA was used in previous version.
Dmesg says DMA us used:
[ 0.000000] Linux version 4.0.4_cpm9g25 (prchal at prchal) (gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-12ubuntu1) ) #5
PREEMPT Wed May 20 12:19:37 CEST 2015
...
[ 16.090090] atmel_usart f801c000.serial: using dma0chan4 for rx DMA transfers
[ 16.105105] atmel_usart f801c000.serial: using dma0chan5 for tx DMA transfers
In 3.18.13 it works properly and dmesg says the same:
[ 0.000000] Linux version 3.18.13_cpm9g25 (prchal at prchal) (gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-12ubuntu1) ) #3
PREEMPT Wed May 20 14:29:26 CEST 2015
...
[ 14.936936] atmel_usart f801c000.serial: using dma0chan4 for rx DMA transfers
[ 14.954954] atmel_usart f801c000.serial: using dma0chan5 for tx DMA transfers
I made diff of drivers/tty/serial/atmel_serial.c and I see many changes in function atmel_rx_from_dma witch I don't
understand. Could it bee there?
All other DMAs work fine.
Jiri
next reply other threads:[~2015-05-20 13:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-20 13:26 Jiří Prchal [this message]
2015-05-27 6:27 ` [BUG] at91: serial: is it using DMA? Jiří Prchal
[not found] ` <556D611A.5090004@aksignal.cz>
2015-06-04 11:33 ` [BUG] at91: serial: something wrong with using DMA Jiří Prchal
2015-06-12 17:01 ` Cyrille Pitchen
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