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Date: Fri, 12 Jun 2015 10:53:35 +0530
From: Vignesh R <vigneshr@ti.com>
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To: Evgeniy Polyakov <zbr@ioremap.net>,
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CC: Tony Lindgren <tony@atomide.com>, NeilBrown <neilb@suse.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Fabian Frederick <fabf@skynet.be>,
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Subject: Re: [PATCH v2] w1: masters: omap_hdq: Add support for 1-wire mode
References: <1431950959-19606-1-git-send-email-vigneshr@ti.com> <5562AFDB.1080701@ti.com> <1072261434036874@web13o.yandex.ru>
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Hi,

On Thursday 11 June 2015 09:04 PM, Evgeniy Polyakov wrote:
> Hi
> 
> 25.05.2015, 08:15, "Vignesh R" <vigneshr@ti.com>:
>>>  HDQ mode remains unchanged.
>>>
>>>  Signed-off-by: Vignesh R <vigneshr@ti.com>
> 
> I have no experience with omap_hdq platform, but there are quite a few questions
> related to IO - you never check whether write was successful or read returned actually
> valid data, is it ok? I mean is it correct to assume that read can not return 0xff for example
> and it is a sign that something is wrong, or this can not happen?
> 

Referring to AM437x TRM SPRUHL7C
(www.ti.com/lit/ug/spruhl7c/spruhl7c.pdf) section 23.3.5.4, Successful
or failed completion is not indicated for write operation, so there is
no way to verify whether write succeeded (though TX_COMPLETE interrupt
bit is set on transaction completion). But, as for as read operation is
concerned, the TRM says, if RX_COMPLETE bit is set, then read is
successful and I think that implies valid data is present in RX reg. My
patch does look for TX/RX_COMPLETE bits to be set after write/read
operations.

> As for me, I have no objection, but this patch must go via omap tree imo.
> 

Andrew Morton has already picked this patch (its on linux-next).
Although he has a minor comment on use of mutex_lock_interruptible. But
that comment applies to many places in the existing driver code. I plan
to cleanup all those mutex calls in near future.

Regards
Vignesh