From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH 20/40] mmc: tegra: Add a workaround for tap value change glitch Date: Thu, 9 Aug 2018 14:58:04 +0200 Message-ID: <20180809125804.GY21639@ulmo> References: <1533141150-10511-1-git-send-email-avienamo@nvidia.com> <1533141150-10511-21-git-send-email-avienamo@nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="B7FF+pnjRCrp0ISR" Return-path: Content-Disposition: inline In-Reply-To: <1533141150-10511-21-git-send-email-avienamo@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Aapo Vienamo Cc: Rob Herring , Mark Rutland , Jonathan Hunter , Ulf Hansson , Adrian Hunter , Mikko Perttunen , Stefan Agner , devicetree@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org List-Id: devicetree@vger.kernel.org --B7FF+pnjRCrp0ISR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Aug 01, 2018 at 07:32:10PM +0300, Aapo Vienamo wrote: > Add quirk to disable the card clock during configuration of the tap > value in tegra_sdhci_set_tap() and issue sdhci_reset() after value > change. This is a workaround to avoid propagation of a potential > glitch caused by setting the tap value. >=20 > Signed-off-by: Aapo Vienamo > --- > drivers/mmc/host/sdhci-tegra.c | 30 ++++++++++++++++++++++++++++-- > 1 file changed, 28 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegr= a.c > index 3c10451..a2375ad 100644 > --- a/drivers/mmc/host/sdhci-tegra.c > +++ b/drivers/mmc/host/sdhci-tegra.c > @@ -47,6 +47,9 @@ > #define SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300 0x20 > #define SDHCI_MISC_CTRL_ENABLE_DDR50 0x200 > =20 > +#define SDHCI_VNDR_TUN_CTRL0_0 0x1c0 > +#define SDHCI_VNDR_TUN_CTRL0_TUN_HW_TAP 0x20000 > + > #define SDHCI_TEGRA_AUTO_CAL_CONFIG 0x1e4 > #define SDHCI_AUTO_CAL_START BIT(31) > #define SDHCI_AUTO_CAL_ENABLE BIT(29) > @@ -68,6 +71,7 @@ > #define NVQUIRK_ENABLE_DDR50 BIT(5) > #define NVQUIRK_HAS_PADCALIB BIT(6) > #define NVQUIRK_NEEDS_PAD_CONTROL BIT(7) > +#define NVQUIRK_DIS_CARD_CLK_CONFIG_TAP BIT(8) > =20 > struct sdhci_tegra_soc_data { > const struct sdhci_pltfm_data *pdata; > @@ -499,12 +503,32 @@ static unsigned int tegra_sdhci_get_max_clock(struc= t sdhci_host *host) > =20 > static void tegra_sdhci_set_tap(struct sdhci_host *host, unsigned int ta= p) > { > + struct sdhci_pltfm_host *pltfm_host =3D sdhci_priv(host); > + struct sdhci_tegra *tegra_host =3D sdhci_pltfm_priv(pltfm_host); > + const struct sdhci_tegra_soc_data *soc_data =3D tegra_host->soc_data; > + bool card_clk_enabled =3D false; > u32 reg; > =20 > + /* > + * Touching the tap values is a bit tricky on some SoC generations. > + * The quirk enables a workaround for a glitch that sometimes occurs if > + * the tap values are changed. > + */ > + > + if (soc_data->nvquirks & NVQUIRK_DIS_CARD_CLK_CONFIG_TAP) > + card_clk_enabled =3D tegra_sdhci_configure_card_clk(host, false); > + > reg =3D sdhci_readl(host, SDHCI_TEGRA_VENDOR_CLOCK_CTRL); > reg &=3D ~SDHCI_CLOCK_CTRL_TAP_MASK; > reg |=3D tap << SDHCI_CLOCK_CTRL_TAP_SHIFT; > sdhci_writel(host, reg, SDHCI_TEGRA_VENDOR_CLOCK_CTRL); > + > + if (soc_data->nvquirks & NVQUIRK_DIS_CARD_CLK_CONFIG_TAP && > + card_clk_enabled) { This is weirdly aligned. > + udelay(1); Can this also become a usleep_range()? I may be too paranoid about this... Thierry > + sdhci_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA); > + tegra_sdhci_configure_card_clk(host, card_clk_enabled); > + } > } > =20 > static int tegra_sdhci_execute_tuning(struct sdhci_host *host, u32 opcod= e) > @@ -758,7 +782,8 @@ static const struct sdhci_pltfm_data sdhci_tegra210_p= data =3D { > static const struct sdhci_tegra_soc_data soc_data_tegra210 =3D { > .pdata =3D &sdhci_tegra210_pdata, > .nvquirks =3D NVQUIRK_NEEDS_PAD_CONTROL | > - NVQUIRK_HAS_PADCALIB, > + NVQUIRK_HAS_PADCALIB | > + NVQUIRK_DIS_CARD_CLK_CONFIG_TAP, > }; > =20 > static const struct sdhci_pltfm_data sdhci_tegra186_pdata =3D { > @@ -783,7 +808,8 @@ static const struct sdhci_pltfm_data sdhci_tegra186_p= data =3D { > static const struct sdhci_tegra_soc_data soc_data_tegra186 =3D { > .pdata =3D &sdhci_tegra186_pdata, > .nvquirks =3D NVQUIRK_NEEDS_PAD_CONTROL | > - NVQUIRK_HAS_PADCALIB, > + NVQUIRK_HAS_PADCALIB | > + NVQUIRK_DIS_CARD_CLK_CONFIG_TAP, > }; > =20 > static const struct of_device_id sdhci_tegra_dt_match[] =3D { > --=20 > 2.7.4 >=20 --B7FF+pnjRCrp0ISR Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAltsOlwACgkQ3SOs138+ s6F0BBAAoaIQAqFlshNymfiyhxa0gQPgVnTkQbJtwzhZGZqYkjfpQNUWWOKzH44l 902s3VSsRE6E0vIPjL3l1P16g/msr6YBCPHcx7M0uICxAdDpYn33RtuxUdsSSysq 6DrGPt4p3iE9+Zigxtl65CdDXKiU9neZOsiJ/SgmdTMIlFAy9hKxjT4EIRspdIYq pa2oLL2b5teaBzvWd0Fshmg7gkDSIEmfrbD/iT+KkMUiOW0wJX4D98f80YSujSwB cel3raQiwOmYo4IcVrO4JV6NKhmrJ60cZTBz/xaIGTm/RzmlR3huoilYGNu4xMpG HCT9IrQa3YkBi07qN+qzPNCzU1gzj+bwdgA5RGv3wd65m0wOWJyxrZOwzc3EbJwo VwqPrxqJqoVorvF42pOHvunPhEGGV6ZqQapvIZBP1ERrG2mOyIZ1sqpBDl78RuKn /HCxpT5Tk55HcJo6S9bkINlNwQs8CSVOostuZUW4WUpp+AI4xCUAkUEFuMY2ZKG3 vzsE2GBwIVHI+Pcd5jQLY1ylecXOoYlTvdmZHk9KHwe+l+pVlnrPRcqDdYFwI/7J ntsVgvIXBT3oqZZgfHpwGirvMvdpjh5Nmx9dnafoaWUvW8ijQqd/sZchHqV2jk3n eHYo41aNTq5EAAdmnyeTxYpOIr5E428edqDUVWx9q2hvPebF610= =b49y -----END PGP SIGNATURE----- --B7FF+pnjRCrp0ISR--