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

From: Greg KH
Date: Mon May 16 2011 - 13:32:02 EST


On Mon, May 16, 2011 at 06:31:18PM +0530, Shreshtha Kumar SAHU wrote:
> From: Shreshtha Kumar Sahu <shreshthakumar.sahu@xxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxx>

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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