On Thu, 6 Aug 2020 at 02:32, Sowjanya Komatineni <skomatineni@xxxxxxxxxx> wrote:
>
> commit b5a84ecf025a ("mmc: tegra: Add Tegra210 support")
>
> Tegra210 and later has a separate sdmmc_legacy_tm (TMCLK) used by Tegra
> SDMMC hawdware for data timeout to achive better timeout than using
> SDCLK and using TMCLK is recommended.
>
> USE_TMCLK_FOR_DATA_TIMEOUT bit in Tegra SDMMC register
> SDHCI_TEGRA_VENDOR_SYS_SW_CTRL can be used to choose either TMCLK or
> SDCLK for data timeout.
>
> Default USE_TMCLK_FOR_DATA_TIMEOUT bit is set to 1 and TMCLK is used
> for data timeout by Tegra SDMMC hardware and having TMCLK not enabled
> is not recommended.
>
> So, this patch fixes it.
Just realized that there should be an updated DT binding accordingly,
stating that the "tmclk" is recommended but optional for some
variants. Please re-spin.
Kind regards
Uffe
>
> Fixes: b5a84ecf025a ("mmc: tegra: Add Tegra210 support")
> Cc: stable <stable@xxxxxxxxxxxxxxx> # 5.4
> Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> ---
> drivers/mmc/host/sdhci-tegra.c | 41 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 41 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index 31ed321..c0b9405 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -140,6 +140,7 @@ struct sdhci_tegra_autocal_offsets {
> struct sdhci_tegra {
> const struct sdhci_tegra_soc_data *soc_data;
> struct gpio_desc *power_gpio;
> + struct clk *tmclk;
> bool ddr_signaling;
> bool pad_calib_required;
> bool pad_control_available;
> @@ -1611,6 +1612,44 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
> goto err_power_req;
> }
>
> + /*
> + * Tegra210 has a separate SDMMC_LEGACY_TM clock used for host
> + * timeout clock and SW can choose TMCLK or SDCLK for hardware
> + * data timeout through the bit USE_TMCLK_FOR_DATA_TIMEOUT of
> + * the register SDHCI_TEGRA_VENDOR_SYS_SW_CTRL.
> + *
> + * USE_TMCLK_FOR_DATA_TIMEOUT bit default is set to 1 and SDMMC uses
> + * 12Mhz TMCLK which is advertised in host capability register.
> + * With TMCLK of 12Mhz provides maximum data timeout period that can
> + * be achieved is 11s better than using SDCLK for data timeout.
> + *
> + * So, TMCLK is set to 12Mhz and kept enabled all the time on SoC's
> + * supporting SDR104 mode and when not using SDCLK for data timeout.
> + */
> +
> + if ((soc_data->nvquirks & NVQUIRK_ENABLE_SDR104) &&
> + !(soc_data->pdata->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)) {
> + clk = devm_clk_get(&pdev->dev, "tmclk");
> + if (IS_ERR(clk)) {
> + rc = PTR_ERR(clk);
> + if (rc == -EPROBE_DEFER)
> + goto err_power_req;
> +
> + dev_warn(&pdev->dev, "failed to get tmclk: %d\n", rc);
> + clk = NULL;
> + }
> +
> + clk_set_rate(clk, 12000000);
> + rc = clk_prepare_enable(clk);
> + if (rc) {
> + dev_err(&pdev->dev,
> + "failed to enable tmclk: %d\n", rc);
> + goto err_power_req;
> + }
> +
> + tegra_host->tmclk = clk;
> + }
> +
> clk = devm_clk_get(mmc_dev(host->mmc), NULL);
> if (IS_ERR(clk)) {
> rc = PTR_ERR(clk);
> @@ -1654,6 +1693,7 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
> err_rst_get:
> clk_disable_unprepare(pltfm_host->clk);
> err_clk_get:
> + clk_disable_unprepare(tegra_host->tmclk);
> err_power_req:
> err_parse_dt:
> sdhci_pltfm_free(pdev);
> @@ -1671,6 +1711,7 @@ static int sdhci_tegra_remove(struct platform_device *pdev)
> reset_control_assert(tegra_host->rst);
> usleep_range(2000, 4000);
> clk_disable_unprepare(pltfm_host->clk);
> + clk_disable_unprepare(tegra_host->tmclk);
>
> sdhci_pltfm_free(pdev);
>
> --
> 2.7.4
>
