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Re: [PATCH][MIPS][5/6]: AR7: serial hack

To: Thomas Bogendoerfer <>
Subject: Re: [PATCH][MIPS][5/6]: AR7: serial hack
From: Sergei Shtylyov <>
Date: Tue, 18 Mar 2008 16:43:44 +0300
Cc: Matteo Croce <>,, Florian Fainelli <>, Felix Fietkau <>, Nicolas Thill <>,, Andrew Morton <>
In-reply-to: <>
Organization: MontaVista Software Inc.
Original-recipient: rfc822;
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Thomas Bogendoerfer wrote:

Il Saturday 15 March 2008 11:40:09 Thomas Bogendoerfer ha scritto:

On Fri, Mar 14, 2008 at 04:46:09PM +0100, Matteo Croce wrote:

This is a bit better

is it possible to try without the serial changes first ?


      uart_port[0].type = PORT_16550A;

in arch/mips/ar7/platform.c.

Does it work ?

Tried I get teh usual broken serial output:

I just checked the latest AR7/UR8 source, I have, and they don't need
special hacks. This is a 2.6.10 based tree. At that time there was
no serial8250_console_putchar(), console output was done via
serial8250_console_write() without any helper. Before writing to the UART_TX, wait_for_xmitr() is called. And this wait_for_xmitr() does
check for BOTH_EMPTY.

Is there a good reason, why we don't check for BOTH_EMPTY in
serial8250_console_putchar() ?

I guess transmission will be slower if you check both THRE and TSRE conditions.

To match the 2.6.10 behaviour we
would need that and this would fix the AR7 case without any
special handling.

AR7 case seems to be the case of bad hardware, and so require special handling...


WBR, Sergei

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