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From: Shubhrajyoti Datta <shubhraj@xilinx.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
	"jirislaby@kernel.org" <jirislaby@kernel.org>,
	"jacmet@sunsite.dk" <jacmet@sunsite.dk>, git <git@xilinx.com>
Subject: RE: [PATCH v2] serial-uartlite: Remove an un-necessary read of control register
Date: Wed, 24 Nov 2021 12:37:00 +0000	[thread overview]
Message-ID: <MN2PR02MB664063C64EA9C8BC59C3E566AA619@MN2PR02MB6640.namprd02.prod.outlook.com> (raw)
In-Reply-To: <YZ4O+qnkVyhGzuDy@kroah.com>



> -----Original Message-----
> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: Wednesday, November 24, 2021 3:38 PM
> To: Shubhrajyoti Datta <shubhraj@xilinx.com>
> Cc: linux-serial@vger.kernel.org; jirislaby@kernel.org; jacmet@sunsite.dk; git
> <git@xilinx.com>
> Subject: Re: [PATCH v2] serial-uartlite: Remove an un-necessary read of control
> register
> 
> On Tue, Nov 23, 2021 at 06:43:48PM +0530, Shubhrajyoti Datta wrote:
> > The control register is a writeonly register that's why reading it
> > doesn't make any sense.
> > The manual states "This is a write-only register. Issuing a read
> > request to the control register generates the read acknowledgment with zero
> data."
> 
> Are you sure this is ok to remove?  Usually you have to do a read after a write to
> ensure that the write succeeded.
> 
> What ensures that the write succeeded now if you remove this read?

I do not find the mention of a read requirement in the manual. 
Also in the current code in ulite_console_write and in ulite_startup we are writing without a 
read. 

Thanks and Regards,
Shubhrajyoti

> 
> thanks,
> 
> greg k-h

  reply	other threads:[~2021-11-24 12:39 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-23 13:13 [PATCH v2] serial-uartlite: Remove an un-necessary read of control register Shubhrajyoti Datta
2021-11-24 10:07 ` Greg KH
2021-11-24 12:37   ` Shubhrajyoti Datta [this message]
2021-11-24 12:45     ` Greg KH
2021-11-26 14:07     ` Maarten Brock
2021-12-15 11:56       ` Michal Simek

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