From: Marek Vasut <marex@denx.de>
To: Krzysztof Adamski <krzysztof.adamski@nokia.com>,
Raviteja Narayanam <raviteja.narayanam@xilinx.com>,
linux-i2c@vger.kernel.org, michal.simek@xilinx.com
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, git@xilinx.com, joe@perches.com
Subject: Re: [PATCH v2 03/10] i2c: xiic: Switch to Xiic standard mode for i2c-read
Date: Wed, 29 Jun 2022 16:34:31 +0200 [thread overview]
Message-ID: <49884f95-5d22-ad65-6ea2-69b0277b096a@denx.de> (raw)
In-Reply-To: <6cf9647e-10dd-8523-962d-a7c40b532fe2@nokia.com>
On 6/29/22 16:09, Krzysztof Adamski wrote:
> Hi Marek,
>
> W dniu 29.06.2022 o 16:05, Marek Vasut pisze:
>>> [...]
>>>
>>> If those two modes only differ in software complexity but we are not
>>> able to support only the simpler one and we have support for the more
>>> complicated (standard mode) anyways, we know that standard mode
>>> can handle or the cases while dynamic mode cannot, we also know that
>>> dynamic mode is broken on some versions of the core, why do we actually
>>> keep support for dynamic mode?
>>
>> If I recall it right, the dynamic mode was supposed to handle
>> transfers longer than 255 Bytes, which the core cannot do in Standard
>> mode. It is needed e.g. by Atmel MXT touch controller. I spent a lot
>> of time debugging the race conditions in the XIIC, which I ultimately
>> fixed (the patches are upstream), but the long transfers I rather
>> fixed in the MXT driver instead.
>>
>> I also recall there was supposed to be some update for the XIIC core
>> coming with newer vivado, but I might be wrong about that.
>
> It seems to be the other way around - dynamic mode is limited to 255
> bytes - when you trigger dynamic mode you first write the address of the
> slave to the FIFO, then you write the length as one byte so you can't
> request more than 255 bytes. So *standard* mode is used for those
> messages. In other words - dynamic mode is the one that is more limited
> - everything that you can do in dynamic mode you can also do in standard
> mode. So why don't we use standard mode always for everything?
Sigh, it's been a year since I looked into this, sorry.
One of the modes is maybe not supported on all the XIIC core instances ?
next prev parent reply other threads:[~2022-06-29 14:34 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-26 10:27 [PATCH v2 00/10] i2c: xiic: Add features, bug fixes Raviteja Narayanam
2021-06-26 10:27 ` [PATCH v2 01/10] i2c: xiic: Fix Tx Interrupt path for grouped messages Raviteja Narayanam
2021-06-26 10:27 ` [PATCH v2 02/10] i2c: xiic: Add standard mode support for > 255 byte read transfers Raviteja Narayanam
2022-06-29 11:02 ` Krzysztof Adamski
2022-06-29 11:39 ` Michal Simek
2022-06-29 12:07 ` Krzysztof Adamski
2021-06-26 10:27 ` [PATCH v2 03/10] i2c: xiic: Switch to Xiic standard mode for i2c-read Raviteja Narayanam
2022-06-29 12:47 ` Krzysztof Adamski
2022-06-29 14:05 ` Marek Vasut
2022-06-29 14:09 ` Krzysztof Adamski
2022-06-29 14:34 ` Marek Vasut [this message]
2022-06-30 8:23 ` Datta, Shubhrajyoti
2022-07-01 7:01 ` Krzysztof Adamski
2022-07-04 5:45 ` Datta, Shubhrajyoti
2021-06-26 10:28 ` [PATCH v2 04/10] i2c: xiic: Remove interrupt enable/disable in Rx path Raviteja Narayanam
2021-06-26 10:28 ` [PATCH v2 05/10] dt-bindings: i2c: xiic: Add 'xlnx,axi-iic-2.1' to compatible Raviteja Narayanam
2021-06-26 10:28 ` [PATCH v2 06/10] i2c: xiic: Update compatible with new IP version Raviteja Narayanam
2021-06-26 10:28 ` [PATCH v2 07/10] i2c: xiic: Return value of xiic_reinit Raviteja Narayanam
2021-06-26 10:28 ` [PATCH v2 08/10] i2c: xiic: Fix the type check for xiic_wakeup Raviteja Narayanam
2021-06-26 10:28 ` [PATCH v2 09/10] i2c: xiic: Fix coding style issues Raviteja Narayanam
2021-06-26 10:28 ` [PATCH v2 10/10] i2c: xiic: Add smbus_block_read functionality Raviteja Narayanam
2021-06-28 7:23 ` [PATCH v2 00/10] i2c: xiic: Add features, bug fixes Michal Simek
2021-07-16 16:01 ` Marek Vasut
2021-07-19 10:09 ` Raviteja Narayanam
2021-07-19 18:00 ` Marek Vasut
2021-07-20 14:19 ` Raviteja Narayanam
2021-07-20 21:43 ` Marek Vasut
2021-07-26 5:26 ` Raviteja Narayanam
2021-07-26 13:12 ` Marek Vasut
2021-07-28 10:11 ` Raviteja Narayanam
2021-07-28 18:47 ` Marek Vasut
2022-06-28 7:50 ` Guntupalli, Manikanta
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=49884f95-5d22-ad65-6ea2-69b0277b096a@denx.de \
--to=marex@denx.de \
--cc=git@xilinx.com \
--cc=joe@perches.com \
--cc=krzysztof.adamski@nokia.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=michal.simek@xilinx.com \
--cc=raviteja.narayanam@xilinx.com \
/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).