From: "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@nokia.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: "Adamski,
Krzysztof (Nokia - PL/Wroclaw)" <krzysztof.adamski@nokia.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>
Subject: Re: [PATCH] axxia-i2c: use auto cmd for last message
Date: Thu, 4 Apr 2019 09:06:43 +0000 [thread overview]
Message-ID: <75b57678-2c55-102a-31ba-2f33bdf5f90b@nokia.com> (raw)
In-Reply-To: <20190403205402.dr2uolmpew45xoxd@ninjato>
Hello Wolfram,
On 03/04/2019 22:54, Wolfram Sang wrote:
>> Some recent commits to this driver were trying to make sure the TSS
>> interrupt is not generated on busy system due to 25ms timer expiring
>> between commands. It can still happen, however if STOP command is not
>> issued on time at the end of the transmission. If wait_for_completion in
>> axxia_i2c_xfer_msg() would not return after 25ms of getting an
>> interrupt, TSS will be generated and idev->err_msg will be set to
>> -ETIMEDOUT which will be returned from the axxia_i2c_xfer_msg(), even
>> though the transfer did actually succeed (STOP is automatically issued
>> when TSS triggers).
>>
>> Fortunately, apart from already used manual and sequence commands, the
>> controller also has so called auto command. It works just like manual
>> mode but it but an automatic STOP is issued when either transfer length
>> is met or NAK is received from slave device.
>>
>> This patch changes the axxia_i2c_xfer_msg() function so that auto
>> command is used for last message in transaction letting hardware manage
>> issuing STOP. TSS is disabled just after command transferring last
>> message finishes. Auto command, just like sequence, ends with SS
>> interrupt instead of SNS so handling of both had to be unified.
>>
>> The axxia_i2c_stop() is no longer needed as the transfer can only end
>> with following conditions:
>> - fully successful - then last message was send by AUTO command and STOP
>> was issued automatically
>> - NAK received - STOP is issued automatically by controller
>> - arbitration lost - STOP should not be issued as we don't control the
>> bus
>> - IP interrupt received - this is sent when transfer length is set to 0
>> for auto/sequence command. The check for that is done before START is
>> send so no STOP is required
>> - TSS received between commands - STOP is issued by the controller
> I am not sure. Is this a bugfix (= for-current) or more a new feature (=
> for-next)?
>
>> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
>> Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
> I trust you that Alexander gave the review, but it would be a tad more
> 'open development' if he could give it as a reply to your patch on the
> mailing list.
sure, here it is:
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
--
Best regards,
Alexander Sverdlin.
next prev parent reply other threads:[~2019-04-04 9:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-28 11:19 [PATCH] axxia-i2c: use auto cmd for last message Adamski, Krzysztof (Nokia - PL/Wroclaw)
2019-04-03 20:54 ` Wolfram Sang
2019-04-03 22:03 ` Adamski, Krzysztof (Nokia - PL/Wroclaw)
2019-04-04 9:06 ` Sverdlin, Alexander (Nokia - DE/Ulm) [this message]
2019-04-15 12:13 ` Wolfram Sang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=75b57678-2c55-102a-31ba-2f33bdf5f90b@nokia.com \
--to=alexander.sverdlin@nokia.com \
--cc=krzysztof.adamski@nokia.com \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=wsa@the-dreams.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).