linux-kernel - Re: [PATCH 1/2] amba pl011: workaround for uart registers lockup

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Message-ID: <20110516172958.GA13011@kroah.com>
Date:	Mon, 16 May 2011 10:29:58 -0700
From:	Greg KH <greg@...ah.com>
To:	Shreshtha Kumar SAHU <shreshthakumar.sahu@...ricsson.com>
Cc:	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
	rmk+kernel@....linux.org.uk, linus.walleij@...ricsson.com,
	alan@...ux.intel.com
Subject: Re: [PATCH 1/2] amba pl011: workaround for uart registers lockup

On Mon, May 16, 2011 at 06:31:18PM +0530, Shreshtha Kumar SAHU wrote:
> From: Shreshtha Kumar Sahu <shreshthakumar.sahu@...ricsson.com>
> 
> This workaround aims to break the deadlock situation
> which raises during continuous transfer of data for long
> duration over uart with hardware flow control. It is
> observed that CTS interrupt cannot be cleared in uart
> interrupt register (ICR). Hence further transfer over
> uart gets blocked.
> 
> It is seen that during such deadlock condition ICR
> don't get cleared even on multiple write. This leads
> pass_counter to decrease and finally reach zero. This
> can be taken as trigger point to run this UART_BT_WA.
> 
> Workaround backups the register configuration, does soft
> reset of UART using BIT-0 of PRCC_K_SOFTRST_SET/CLEAR
> registers and restores the registers.
> 
> This patch also provides support for uart init and exit
> function calls if present.
> 
> Signed-off-by: Shreshtha Kumar Sahu <shreshthakumar.sahu@...ricsson.com>

Please always run your patches through scripts/checkpatch.pl so we don't
end up telling you to fix up the same obvious things that this tool
would tell you needs to be fixed...

thanks,

greg k-h
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