From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH v2] MMC: tmio: fix unbalanced power-on calls with clock-gating enabled Date: Thu, 25 Apr 2013 00:16:23 +0200 Message-ID: <3768014.CvXq4XhzdR@avalon> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:46246 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758439Ab3DXWQZ (ORCPT ); Wed, 24 Apr 2013 18:16:25 -0400 In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Guennadi Liakhovetski Cc: linux-mmc@vger.kernel.org, linux-sh@vger.kernel.org, Chris Ball Hi Guennadi, Thanks for the patch. On Tuesday 23 April 2013 09:29:44 Guennadi Liakhovetski wrote: > With MMC clock gating enabled the MMC core currently calls MMC host driver's > .set_ios() method with .power_mode == MMC_POWER_ON and the clock value set > either to 0 or to the target rate. The tmio MMC driver then wrongly > translates the latter calls to card slot power-on requests, even when the > slot already was on. This patch fixes the driver to avoid needlessly > incrementing power-supplying regulator's use count. > > Signed-off-by: Guennadi Liakhovetski Tested-by: Laurent Pinchart With this patch the number of users of the vqmmc regulator stays at 1 (regardless of whether the card is inserted or now). > --- > > v2: Also make runtime PM handling safer and more resistant to possible > MMC core changes. V1 worked fine too, but theoretically if the core > decided to issue a sequence like > > .set_ios(ios->power_mode == MMC_POWER_ON, ios->clock != 0); > .set_ios(ios->power_mode == MMC_POWER_ON, ios->clock == 0); > .set_ios(ios->power_mode == MMC_POWER_OFF, ios->clock == 0); > > we would end up calling pm_runtime_put() twice in a row, which is wrong. > V2 only toggles the controller runtime PM status only when entering or > leaving the TMIO_MMC_ON_RUN state. > > drivers/mmc/host/tmio_mmc.h | 20 ++++++++++++++++++-- > drivers/mmc/host/tmio_mmc_pio.c | 27 +++++++++++++++++---------- > 2 files changed, 35 insertions(+), 12 deletions(-) > > diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h > index d857f5c..3cc589a 100644 > --- a/drivers/mmc/host/tmio_mmc.h > +++ b/drivers/mmc/host/tmio_mmc.h > @@ -40,6 +40,22 @@ > > struct tmio_mmc_data; > > +/* > + * We differentiate between the following 3 power states: > + * 1. card slot powered off, controller stopped. This is used, when either > there + * is no card in the slot, or the card really has to be powered > down. + * 2. card slot powered on, controller stopped. This is used, when a > card is in + * the slot, but no activity is currently taking place. This > is a power- + * saving mode with card-state preserved. This state can be > entered, e.g. + * when MMC clock-gating is used. > + * 3. card slot powered on, controller running. This is the actual active > state. + */ > +enum tmio_mmc_power { > + TMIO_MMC_OFF_STOP, /* card power off, controller stopped */ > + TMIO_MMC_ON_STOP, /* card power on, controller stopped */ > + TMIO_MMC_ON_RUN, /* card power on, controller running */ > +}; > + > struct tmio_mmc_host { > void __iomem *ctl; > unsigned long bus_shift; > @@ -48,8 +64,8 @@ struct tmio_mmc_host { > struct mmc_data *data; > struct mmc_host *mmc; > > - /* Controller power state */ > - bool power; > + /* Controller and card power state */ > + enum tmio_mmc_power power; > > /* Callbacks for clock / power control */ > void (*set_pwr)(struct platform_device *host, int state); > diff --git a/drivers/mmc/host/tmio_mmc_pio.c > b/drivers/mmc/host/tmio_mmc_pio.c index f508ecb..1d5ef64 100644 > --- a/drivers/mmc/host/tmio_mmc_pio.c > +++ b/drivers/mmc/host/tmio_mmc_pio.c > @@ -859,32 +859,39 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, > struct mmc_ios *ios) * is kept positive, so no suspending actually takes > place. > */ > if (ios->power_mode == MMC_POWER_ON && ios->clock) { > - if (!host->power) { > + if (host->power != TMIO_MMC_ON_RUN) { > tmio_mmc_clk_update(mmc); > pm_runtime_get_sync(dev); > } > tmio_mmc_set_clock(host, ios->clock); > - if (!host->power) { > + if (host->power == TMIO_MMC_OFF_STOP) > /* power up SD card and the bus */ > tmio_mmc_power_on(host, ios->vdd); > - host->power = true; > - } > + host->power = TMIO_MMC_ON_RUN; > /* start bus clock */ > tmio_mmc_clk_start(host); > } else if (ios->power_mode != MMC_POWER_UP) { > - if (host->power) { > - struct tmio_mmc_data *pdata = host->pdata; > - if (ios->power_mode == MMC_POWER_OFF) > + struct tmio_mmc_data *pdata = host->pdata; > + unsigned int old_power = host->power; > + > + if (old_power != TMIO_MMC_OFF_STOP) { > + if (ios->power_mode == MMC_POWER_OFF) { > tmio_mmc_power_off(host); > + host->power = TMIO_MMC_OFF_STOP; > + } else { > + host->power = TMIO_MMC_ON_STOP; > + } > + } > + > + if (old_power == TMIO_MMC_ON_RUN) { > tmio_mmc_clk_stop(host); > - host->power = false; > pm_runtime_put(dev); > if (pdata->clk_disable) > pdata->clk_disable(host->pdev); > } > } > > - if (host->power) { > + if (host->power != TMIO_MMC_OFF_STOP) { > switch (ios->bus_width) { > case MMC_BUS_WIDTH_1: > sd_ctrl_write16(host, CTL_SD_MEM_CARD_OPT, 0x80e0); > @@ -1025,7 +1032,7 @@ int tmio_mmc_host_probe(struct tmio_mmc_host **host, > mmc->caps & MMC_CAP_NONREMOVABLE || > mmc->slot.cd_irq >= 0); > > - _host->power = false; > + _host->power = TMIO_MMC_OFF_STOP; > pm_runtime_enable(&pdev->dev); > ret = pm_runtime_resume(&pdev->dev); > if (ret < 0) -- Regards, Laurent Pinchart