From: Ulf Hansson <ulf.hansson@linaro.org>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>,
Simon Horman <horms+renesas@verge.net.au>,
Magnus Damm <magnus.damm@gmail.com>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH v3 0/2] mmc: renesas_sdhi: add eMMC HS400 mode support
Date: Tue, 27 Feb 2018 11:13:13 +0100 [thread overview]
Message-ID: <CAPDyKFqMacY1THjO+cTb6Aws3mCnbLogui9T6PjiVcoR89FiLg@mail.gmail.com> (raw)
In-Reply-To: <20180227090757.wvm6j4sy5nmeecf3@katana>
On 27 February 2018 at 10:07, Wolfram Sang <wsa@the-dreams.de> wrote:
>
>> Is this ready to be queued up for next? It looks good to me.
>
> Ulf, out of your head, do you have an idea why preparing HS400 during
> set_ios works but populating host->ops->prepare_hs400_tuning() does not
> (according to Simon's tests)?
Oh, that sounds weird. Obviously I didn't read the code carefully enough.
Preparing tuning (if needed, as this is optional) needs to be done
prior mmc->ios.timing is set to MMC_TIMING_MMC_HS400, because the
tuning has already been done when we reach that point.
There seems to be something fishy going on here, as there seemed to be
some kind of reset sequence being added and executed as well.
Perhaps someone need to explain in more detail what the HW controller
needs to manage tuning for HS400? I don't like that we may end up
getting it magically to work, then it's we better understand the
details and if the current sequence provided by the mmc core can't
fulfill the need for this case, we may instead consider adding an
additional pre/post host ops.
Hope this helps!
Kind regards
Uffe
next prev parent reply other threads:[~2018-02-27 10:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-13 12:33 [PATCH v3 0/2] mmc: renesas_sdhi: add eMMC HS400 mode support Simon Horman
2018-02-13 12:33 ` [PATCH v3 1/2] mmc: tmio: " Simon Horman
2018-02-13 12:33 ` [PATCH v3 2/2] mmc: renesas_sdhi: " Simon Horman
2018-02-27 7:53 ` [PATCH v3 0/2] " Ulf Hansson
2018-02-27 8:26 ` Simon Horman
2018-02-27 9:07 ` Wolfram Sang
2018-02-27 10:13 ` Ulf Hansson [this message]
2018-02-27 13:02 ` Wolfram Sang
2018-03-27 11:12 ` Simon Horman
2018-04-05 7:30 ` Ulf Hansson
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