linux-kernel - Re: [PATCH v2] mmc: sdhci-of-arasan: fix set

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Date:	Wed, 04 May 2016 10:35:21 +0200
From:	Heiko Stuebner <heiko@...ech.de>
To:	Shawn Lin <shawn.lin@...k-chips.com>
Cc:	Ulf Hansson <ulf.hansson@...aro.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Michal Simek <michal.simek@...inx.com>,
	Sören Brinkmann <soren.brinkmann@...inx.com>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Doug Anderson <dianders@...omium.org>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH v2] mmc: sdhci-of-arasan: fix set_clock when a phy is supported

Am Mittwoch, 4. Mai 2016, 09:48:55 schrieb Shawn Lin:
> 在 2016/4/28 18:38, Ulf Hansson 写道:
> > On 28 April 2016 at 10:38, Shawn Lin <shawn.lin@...k-chips.com> wrote:
> >> commit 61b914eb81f8 ("mmc: sdhci-of-arasan: add phy support for
> >> sdhci-of-arasan") introduce phy support for arasan. According to
> >> the vendor's databook, we should make sure the phy is in poweroff
> >> status before we configure the clk stuff. Otherwise it may cause
> >> some IO sample timing issues from the test. And we don't need this
> >> extra operation while running in low performance mode since phy
> >> doesn't trigger sampling block.
> >> 
> >> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
> > 
> > Thanks, applied for next!
> 
> Thanks for applying v2 but, could you please drop it and applied v3
> I just send :) .
> Because v2 introduces a bug. Set_clock callback will be
> called under the protection of spinlock in sdhci_do_set_ios. However
> PHY APIs need mutex which fails the kernel's debug check
> 
> BUG: sleeping function called from invalid context at
> kernel/locking/mutex.c

I think in general you will need to provide a follow-up patch instead of 
replacing the old version, as Ulf might not want to restructure an already 
published branch (depends on the maintainer), especially as already other 
stuff is on top of your patch [0].


Heiko

[0] 
https://git.linaro.org/people/ulf.hansson/mmc.git/shortlog/refs/heads/next




> > Kind regards
> > Uffe
> > 
> >> ---
> >> 
> >> Changes in v2:
> >> - change commit msg title to indicate it's a fix
> >> - fix a typo in commmit msg
> >> 
> >>  drivers/mmc/host/sdhci-of-arasan.c | 20 +++++++++++++++++++-
> >>  1 file changed, 19 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/mmc/host/sdhci-of-arasan.c
> >> b/drivers/mmc/host/sdhci-of-arasan.c index 2e482b1..20b859e 100644
> >> --- a/drivers/mmc/host/sdhci-of-arasan.c
> >> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> >> @@ -55,8 +55,26 @@ static unsigned int
> >> sdhci_arasan_get_timeout_clock(struct sdhci_host *host)>> 
> >>         return freq;
> >>  
> >>  }
> >> 
> >> +static void sdhci_arasan_set_clock(struct sdhci_host *host, unsigned
> >> int clock) +{
> >> +       struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> >> +       struct sdhci_arasan_data *sdhci_arasan =
> >> sdhci_pltfm_priv(pltfm_host); +       bool ctrl_phy = false;
> >> +
> >> +       if (clock > MMC_HIGH_52_MAX_DTR &&
> >> (!IS_ERR(sdhci_arasan->phy)))
> >> +               ctrl_phy = true;
> >> +
> >> +       if (ctrl_phy)
> >> +               phy_power_off(sdhci_arasan->phy);
> >> +
> >> +       sdhci_set_clock(host, clock);
> >> +
> >> +       if (ctrl_phy)
> >> +               phy_power_on(sdhci_arasan->phy);
> >> +}
> >> +
> >> 
> >>  static struct sdhci_ops sdhci_arasan_ops = {
> >> 
> >> -       .set_clock = sdhci_set_clock,
> >> +       .set_clock = sdhci_arasan_set_clock,
> >> 
> >>         .get_max_clock = sdhci_pltfm_clk_get_max_clock,
> >>         .get_timeout_clock = sdhci_arasan_get_timeout_clock,
> >>         .set_bus_width = sdhci_set_bus_width,
> >> 
> >> --
> >> 2.3.7
> >> 
> >> 
> >> --
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