linux-kernel - Re: [PATCH 2/2] msm: Support DEBUG

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Date:	Thu, 29 Sep 2011 00:21:29 -0400 (EDT)
From:	Nicolas Pitre <nico@...xnic.net>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	David Brown <davidb@...eaurora.org>, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] msm: Support DEBUG_LL on MSM8660 and MSM8960

On Wed, 28 Sep 2011, Stephen Boyd wrote:

> Add support for DEBUG_LL on the 8660 and 8960 development boards.
> While we're here, cleanup the uncompress.h code a bit.
> 
> Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
> ---

[...]

>  	.macro	senduart,rd,rx
> +#ifdef CONFIG_MSM_HAS_DEBUG_UART_HS
> +	@ Clear TX_READY by writing to the UARTDM_CR register
> +	mov	r12, #0x300
> +	str	r12, [\rx, #0x10]
> +	@ Write 0x1 to NCF register
> +	mov 	r12, #0x1
> +	str	r12, [\rx, #0x40]
> +	@ UARTDM reg. Read to induce delay
> +	ldr	r12, [\rx, #0x08]
> +	@ Write the 1 character to UARTDM_TF
> +	str	\rd, [\rx, #0x70]

This is a really bad idea to pick a register (r12) when the calling code 
is completely unaware of that.  This _will_ break on you someday.

Except for the last line, why didn't you simply fold this code into the 
waituart macro instead?


Nicolas
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