From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [PATCH v2 11/40] mmc: sdhci: Add a quirk to skip clearing the transfer mode register on tuning Date: Mon, 27 Aug 2018 14:01:52 +0300 Message-ID: References: <1533924522-1037-1-git-send-email-avienamo@nvidia.com> <1533924522-1037-12-git-send-email-avienamo@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1533924522-1037-12-git-send-email-avienamo@nvidia.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Aapo Vienamo , Rob Herring , Mark Rutland , Thierry Reding , Jonathan Hunter , Ulf Hansson , Mikko Perttunen , Stefan Agner Cc: 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 On 10/08/18 21:08, Aapo Vienamo wrote: > Add SDHCI_QUIRK2_TUNE_SKIP_XFERRMODE_REG_PROG to skip programming the > SDHCI_TRANSFER_MODE in sdhci_set_transfer_mode() if tuning command is > being sent. > > On Tegra210 and Tegra186 the tuning sequence hangs if the SDHCI > transfer mode register is touched. > > Signed-off-by: Aapo Vienamo > --- > drivers/mmc/host/sdhci.c | 6 ++++++ > drivers/mmc/host/sdhci.h | 2 ++ > 2 files changed, 8 insertions(+) > > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c > index a7b5602..04dc443 100644 > --- a/drivers/mmc/host/sdhci.c > +++ b/drivers/mmc/host/sdhci.c > @@ -1028,6 +1028,12 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host, > > if (data == NULL) { > if (host->quirks2 & > + SDHCI_QUIRK2_TUNE_SKIP_XFERMODE_REG_PROG && > + (cmd->opcode == MMC_SEND_TUNING_BLOCK || > + cmd->opcode == MMC_SEND_TUNING_BLOCK_HS200)) { > + return; > + } Rather than introduce a quirk, can't we just dodge the unnecessary write e.g. diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 1b3fbd9bd5c5..68af6a67e397 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -1033,10 +1033,19 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host, if (cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200) sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE); } else { - /* clear Auto CMD settings for no data CMDs */ + u16 orig; + + /* clear Auto CMD settings for no data CMDs */ mode = sdhci_readw(host, SDHCI_TRANSFER_MODE); - sdhci_writew(host, mode & ~(SDHCI_TRNS_AUTO_CMD12 | - SDHCI_TRNS_AUTO_CMD23), SDHCI_TRANSFER_MODE); + orig = mode; + mode &= ~(SDHCI_TRNS_AUTO_CMD12 | SDHCI_TRNS_AUTO_CMD23); + /* + * Do not write transfer mode unnecessarily because it + * can upset some host controllers (e.g. sdhci-tregra) + * during tuning. + */ + if (mode != orig) + sdhci_writew(host, new_mode, SDHCI_TRANSFER_MODE); } return; } Alternatively > + if (host->quirks2 & > SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD) { > sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE); > } else { > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h > index 23966f8..0a99008 100644 > --- a/drivers/mmc/host/sdhci.h > +++ b/drivers/mmc/host/sdhci.h > @@ -450,6 +450,8 @@ struct sdhci_host { > * obtainable timeout. > */ > #define SDHCI_QUIRK2_DISABLE_HW_TIMEOUT (1<<17) > +/* Don't clear the SDHCI_TRANSFER_MODE register on tuning commands */ > +#define SDHCI_QUIRK2_TUNE_SKIP_XFERMODE_REG_PROG (1<<18) > > int irq; /* Device IRQ */ > void __iomem *ioaddr; /* Mapped address */ >