On 8/5/20 1:06 AM, Adrian Hunter wrote:
On 4/08/20 7:29 am, Sowjanya Komatineni wrote:
commit b5a84ecf025a ("mmc: tegra: Add Tegra210 support")
So that could be a Fixes tag also?
Thanks Adrian. Will resend with fixes tag.
Sowjanya
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.
Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
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);
