From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aapo Vienamo Subject: Re: [PATCH 09/10] mmc: tegra: Perform pad calibration after voltage switch Date: Wed, 25 Jul 2018 13:43:00 +0300 Message-ID: <20180725134300.7e537ceb@dhcp-10-21-25-168> References: <1532442591-5640-1-git-send-email-avienamo@nvidia.com> <1532442865-6391-1-git-send-email-avienamo@nvidia.com> <1532442865-6391-8-git-send-email-avienamo@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Mikko Perttunen Cc: Ulf Hansson , Rob Herring , Mark Rutland , Thierry Reding , Jonathan Hunter , Adrian Hunter , Mikko Perttunen , linux-mmc@vger.kernel.org, devicetree@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: devicetree@vger.kernel.org On Wed, 25 Jul 2018 10:25:16 +0300 Mikko Perttunen wrote: > On 24.07.2018 17:34, Aapo Vienamo wrote: > > Run the automatic pad calibration after voltage switching if > > tegra_host->pad_calib_required is set. > > > > Signed-off-by: Aapo Vienamo > > --- > > drivers/mmc/host/sdhci-tegra.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c > > index 78781bd..529aa4e7 100644 > > --- a/drivers/mmc/host/sdhci-tegra.c > > +++ b/drivers/mmc/host/sdhci-tegra.c > > @@ -537,6 +537,8 @@ static int sdhci_tegra_start_signal_voltage_switch(struct mmc_host *mmc, > > struct mmc_ios *ios) > > { > > struct sdhci_host *host = mmc_priv(mmc); > > + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); > > + struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host); > > int ret = 0; > > > > if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330) { > > @@ -551,6 +553,9 @@ static int sdhci_tegra_start_signal_voltage_switch(struct mmc_host *mmc, > > ret = tegra_sdhci_set_padctrl(host, ios->signal_voltage); > > } > > > > + if (tegra_host->pad_calib_required) > > + tegra_sdhci_pad_autocalib(host); > > What if the autocalibration fails? Should we return an error? I would assume that aborting the signal voltage switch due to a calibration timeout would not be necessary as the TRM specifies drive strength values which are to be programmed in case a timeout occurs. However, I don't know what are the exact implications of running the bus with the timeout values instead of the calibrated ones. The TRM does not comment on that. I guess tuning would fail and catch the error that way in case the timeout default values aren't sufficient. -Aapo > > + > > return ret; > > } > > > >