From: Kevin Hilman <khilman@baylibre.com>
To: Jerome Brunet <jbrunet@baylibre.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>,
Carlo Caione <carlo@caione.org>,
linux-mmc@vger.kernel.org, linux-amlogic@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 13/14] mmc: meson-gx: work around clk-stop issue
Date: Mon, 07 Aug 2017 14:41:57 -0700 [thread overview]
Message-ID: <7hzibbnjh6.fsf@baylibre.com> (raw)
In-Reply-To: <20170804174353.16486-14-jbrunet@baylibre.com> (Jerome Brunet's message of "Fri, 4 Aug 2017 19:43:52 +0200")
Jerome Brunet <jbrunet@baylibre.com> writes:
> It seems that the signal clock is also used and required, somehow, by
> the controller it self.
>
> It is shown during init, when writing to CFG while the divider is set
> to 0 will crash the SoC. During voltage switch, the controller may crash
> and the card may then fail to exit busy state if the clock is stopped.
>
> To avoid this, it is best to keep the clock running for the controller,
> except during rate change. However, we still need to be able to gate
> the clock out of the SoC. Let's use the pinmux for this, and fallback
> to gpio mode (pulled-down) when we need to gate the clock
>
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Curious "feature" of the IP, but the solution looks good to me.
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Kevin
next prev parent reply other threads:[~2017-08-07 21:42 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-04 17:43 [PATCH 00/14] mmc: meson-gx: driver fixups and upgrade Jerome Brunet
2017-08-04 17:43 ` [PATCH 01/14] mmc: meson-gx: fix mux mask definition Jerome Brunet
2017-08-04 17:43 ` [PATCH 02/14] mmc: meson-gx: remove CLK_DIVIDER_ALLOW_ZERO clock flag Jerome Brunet
2017-08-04 17:43 ` [PATCH 03/14] mmc: meson-gx: clean up some constants Jerome Brunet
2017-08-07 21:06 ` Kevin Hilman
2017-08-21 11:54 ` Jerome Brunet
2017-08-04 17:43 ` [PATCH 04/14] mmc: meson-gx: use _irqsave variant of spinlock Jerome Brunet
2017-08-04 17:43 ` [PATCH 05/14] mmc: meson-gx: cfg init overwrite values Jerome Brunet
2017-08-04 17:43 ` [PATCH 06/14] mmc: meson-gx: rework set_ios function Jerome Brunet
2017-08-04 17:43 ` [PATCH 07/14] mmc: meson-gx: rework clk_set function Jerome Brunet
2017-08-04 17:43 ` [PATCH 08/14] mmc: meson-gx: rework clock init function Jerome Brunet
2017-08-07 21:34 ` Kevin Hilman
2017-08-21 12:05 ` Jerome Brunet
2017-08-04 17:43 ` [PATCH 09/14] mmc: meson-gx: simplify interrupt handler Jerome Brunet
2017-08-04 17:43 ` [PATCH 10/14] mmc: meson-gx: implement card_busy callback Jerome Brunet
2017-08-04 17:43 ` [PATCH 11/14] mmc: meson-gx: rework tuning function Jerome Brunet
2017-08-04 17:43 ` [PATCH 12/14] mmc: meson-gx: fix dual data rate mode frequencies Jerome Brunet
2017-08-04 17:43 ` [PATCH 13/14] mmc: meson-gx: work around clk-stop issue Jerome Brunet
2017-08-07 21:41 ` Kevin Hilman [this message]
2017-08-04 17:43 ` [PATCH 14/14] mmc: meson-gx: implement voltage switch callback Jerome Brunet
2017-08-07 16:48 ` [PATCH 00/14] mmc: meson-gx: driver fixups and upgrade Jerome Brunet
2017-08-07 21:44 ` Kevin Hilman
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