From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Alan Cox <alan@linux.intel.com>,
Vitaly Bordug <vitb@kernel.crashing.org>,
Marcelo Tosatti <marcelo@kvack.org>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-serial@vger.kernel.org
Subject: [PATCH] Powerpc 8xx CPM_UART delay in receive
Date: Tue, 14 Aug 2012 16:26:28 +0200 [thread overview]
Message-ID: <201208141426.q7EEQSPc003956@localhost.localdomain> (raw)
Hello,
I'm not sure who to address this Patch to either
It fixes a delay issue with CPM UART driver on Powerpc MPC8xx.
The problem is that with the actual code, the driver waits 32 IDLE patterns before returning the received data to the upper level. It means for instance about 1 second at 300 bauds.
This fix limits to one byte the waiting period.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
--- linux-3.5-vanilla/drivers/tty/serial/cpm_uart/cpm_uart_core.c 2012-07-21 22:58:29.000000000 +0200
+++ linux-3.5/drivers/tty/serial/cpm_uart/cpm_uart_core.c 2012-08-09 17:38:37.000000000 +0200
@@ -798,7 +799,7 @@
cpm_set_scc_fcr(sup);
out_be16(&sup->scc_genscc.scc_mrblr, pinfo->rx_fifosize);
- out_be16(&sup->scc_maxidl, pinfo->rx_fifosize);
+ out_be16(&sup->scc_maxidl, 1);
out_be16(&sup->scc_brkcr, 1);
out_be16(&sup->scc_parec, 0);
out_be16(&sup->scc_frmec, 0);
@@ -872,7 +873,7 @@
/* Using idle character time requires some additional tuning. */
out_be16(&up->smc_mrblr, pinfo->rx_fifosize);
- out_be16(&up->smc_maxidl, pinfo->rx_fifosize);
+ out_be16(&up->smc_maxidl, 1);
out_be16(&up->smc_brklen, 0);
out_be16(&up->smc_brkec, 0);
out_be16(&up->smc_brkcr, 1);
next reply other threads:[~2012-08-14 15:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-14 14:26 Christophe Leroy [this message]
2012-08-14 14:52 ` [PATCH] Powerpc 8xx CPM_UART delay in receive Alan Cox
2012-08-16 13:16 ` leroy christophe
2012-08-16 14:29 ` Alan Cox
2012-08-16 14:35 ` leroy christophe
2012-08-16 15:21 ` Alan Cox
2012-09-10 7:09 ` leroy christophe
2012-09-10 13:10 ` Alan Cox
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