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Date: Thu, 27 Aug 2020 09:40:06 +0100
From: Jon Hunter <jonathanh@...dia.com>
To: Sowjanya Komatineni <skomatineni@...dia.com>,
<adrian.hunter@...el.com>, <ulf.hansson@...aro.org>,
<thierry.reding@...il.com>, <robh+dt@...nel.org>
CC: <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-mmc@...r.kernel.org>, <devicetree@...r.kernel.org>,
<stable@...r.kernel.org>
Subject: Re: [PATCH v6 7/7] sdhci: tegra: Add missing TMCLK for data timeout
On 27/08/2020 04:50, Sowjanya Komatineni 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 adds quirk NVQUIRK_HAS_TMCLK for SoC having separate
> timeout clock and keeps TMCLK enabled all the time.
>
> Fixes: b5a84ecf025a ("mmc: tegra: Add Tegra210 support")
> Cc: stable <stable@...r.kernel.org> # 5.4
> Tested-by: Jon Hunter <jonathanh@...dia.com>
> Reviewed-by: Jon Hunter <jonathanh@...dia.com>
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>
> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
> ---
> drivers/mmc/host/sdhci-tegra.c | 90 ++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 82 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index 31ed321..f69ca8d 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -13,6 +13,7 @@
> #include <linux/clk.h>
> #include <linux/io.h>
> #include <linux/of.h>
> +#include <linux/of_clk.h>
> #include <linux/of_device.h>
> #include <linux/pinctrl/consumer.h>
> #include <linux/regulator/consumer.h>
> @@ -110,6 +111,12 @@
> #define NVQUIRK_DIS_CARD_CLK_CONFIG_TAP BIT(8)
> #define NVQUIRK_CQHCI_DCMD_R1B_CMD_TIMING BIT(9)
>
> +/*
> + * NVQUIRK_HAS_TMCLK is for SoC's having separate timeout clock for Tegra
> + * SDMMC hardware data timeout.
> + */
> +#define NVQUIRK_HAS_TMCLK BIT(10)
> +
> /* SDMMC CQE Base Address for Tegra Host Ver 4.1 and Higher */
> #define SDHCI_TEGRA_CQE_BASE_ADDR 0xF000
>
> @@ -140,6 +147,7 @@ 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;
> @@ -1433,7 +1441,8 @@ static const struct sdhci_tegra_soc_data soc_data_tegra210 = {
> NVQUIRK_HAS_PADCALIB |
> NVQUIRK_DIS_CARD_CLK_CONFIG_TAP |
> NVQUIRK_ENABLE_SDR50 |
> - NVQUIRK_ENABLE_SDR104,
> + NVQUIRK_ENABLE_SDR104 |
> + NVQUIRK_HAS_TMCLK,
> .min_tap_delay = 106,
> .max_tap_delay = 185,
> };
> @@ -1471,6 +1480,7 @@ static const struct sdhci_tegra_soc_data soc_data_tegra186 = {
> NVQUIRK_DIS_CARD_CLK_CONFIG_TAP |
> NVQUIRK_ENABLE_SDR50 |
> NVQUIRK_ENABLE_SDR104 |
> + NVQUIRK_HAS_TMCLK |
> NVQUIRK_CQHCI_DCMD_R1B_CMD_TIMING,
> .min_tap_delay = 84,
> .max_tap_delay = 136,
> @@ -1483,7 +1493,8 @@ static const struct sdhci_tegra_soc_data soc_data_tegra194 = {
> NVQUIRK_HAS_PADCALIB |
> NVQUIRK_DIS_CARD_CLK_CONFIG_TAP |
> NVQUIRK_ENABLE_SDR50 |
> - NVQUIRK_ENABLE_SDR104,
> + NVQUIRK_ENABLE_SDR104 |
> + NVQUIRK_HAS_TMCLK,
> .min_tap_delay = 96,
> .max_tap_delay = 139,
> };
> @@ -1611,15 +1622,76 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
> goto err_power_req;
> }
>
> - clk = devm_clk_get(mmc_dev(host->mmc), NULL);
> - if (IS_ERR(clk)) {
> - rc = PTR_ERR(clk);
> + /*
> + * Tegra210 and later has separate SDMMC_LEGACY_TM clock used for
> + * hardware data 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 separate TMCLK.
> + *
> + * Old device tree has single sdhci clock. So with addition of TMCLK,
> + * retrieving sdhci clock by "sdhci" clock name based on number of
> + * clocks in sdhci device node.
> + */
> +
> + if (of_clk_get_parent_count(pdev->dev.of_node) == 1) {
> + if (soc_data->nvquirks & NVQUIRK_HAS_TMCLK)
> + dev_warn(&pdev->dev,
> + "missing tmclk in the device tree\n");
> +
> + clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(clk)) {
> + rc = PTR_ERR(clk);
>
> - if (rc != -EPROBE_DEFER)
> - dev_err(&pdev->dev, "failed to get clock: %d\n", rc);
> + if (rc != -EPROBE_DEFER)
> + dev_err(&pdev->dev,
> + "failed to get sdhci clock: %d\n", rc);
>
> - goto err_clk_get;
> + goto err_power_req;
> + }
> + } else {
> + if (soc_data->nvquirks & NVQUIRK_HAS_TMCLK) {
I think that I would do the inverse of this ...
} else {
if (!(soc_data->nvquirks & NVQUIRK_HAS_TMCLK)) {
dev_err(&pdev->dev, "Device has unexpected clocks!\n");
rc = -EINVAL;
goto_power_req;
}
clk = devm_clk_get(&pdev->dev, "tmclk");
...
If the device does not have a single clock, then we expect it to support
the tmclk. If this is not the case, then this is a bug.
Cheers
Jon
--
nvpublic
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