Re: [PATCH 2/8] mmc: tegra: Parse and program DQS trim value
From: Thierry Reding <hidden>
Date: 2018-08-09 11:40:52
Also in:
linux-mmc, linux-tegra, lkml
On Tue, Aug 07, 2018 at 04:59:58PM +0300, Aapo Vienamo wrote:
quoted hunk ↗ jump to hunk
Parse and program the HS400 DQS trim value from dt. Program a fallback value in case the property is missing. Signed-off-by: Aapo Vienamo <redacted> --- drivers/mmc/host/sdhci-tegra.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-)diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c index 7f1ac4a..426f7ea 100644 --- a/drivers/mmc/host/sdhci-tegra.c +++ b/drivers/mmc/host/sdhci-tegra.c@@ -43,6 +43,10 @@ #define SDHCI_CLOCK_CTRL_PADPIPE_CLKEN_OVERRIDE BIT(3) #define SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE BIT(2) +#define SDHCI_TEGRA_VENDOR_CAP_OVERRIDES 0x10c +#define SDHCI_TEGRA_CAP_OVERRIDES_DQS_TRIM_MASK 0x00003f00 +#define SDHCI_TEGRA_CAP_OVERRIDES_DQS_TRIM_SHIFT 8 + #define SDHCI_TEGRA_VENDOR_MISC_CTRL 0x120 #define SDHCI_MISC_CTRL_ENABLE_SDR104 0x8 #define SDHCI_MISC_CTRL_ENABLE_SDR50 0x10@@ -112,6 +116,7 @@ struct sdhci_tegra { u32 default_tap; u32 default_trim; + u32 dqs_trim; }; static u16 tegra_sdhci_readw(struct sdhci_host *host, int reg)@@ -500,7 +505,7 @@ static void tegra_sdhci_parse_pad_autocal_dt(struct sdhci_host *host) autocal->pull_down_hs400 = autocal->pull_down_1v8; } -static void tegra_sdhci_parse_default_tap_and_trim(struct sdhci_host *host) +static void tegra_sdhci_parse_tap_and_trim(struct sdhci_host *host) { struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);@@ -515,6 +520,11 @@ static void tegra_sdhci_parse_default_tap_and_trim(struct sdhci_host *host) &tegra_host->default_trim); if (err) tegra_host->default_trim = 0; + + err = device_property_read_u32(host->mmc->parent, "nvidia,dqs-trim", + &tegra_host->dqs_trim); + if (err) + tegra_host->dqs_trim = 0x11;
Okay, so there's only one value. I think that should be clarified in the bindings documentation. It should mention that a single cell is used for this. Also, I assume there are lower and upper limits for the valid range of DQS trim values. Might make sense to specify those in the DT bindings as well.
quoted hunk ↗ jump to hunk
} static void tegra_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)@@ -545,20 +555,33 @@ static unsigned int tegra_sdhci_get_max_clock(struct sdhci_host *host) return clk_round_rate(pltfm_host->clk, UINT_MAX); } +static void tegra_sdhci_set_dqs_trim(struct sdhci_host *host, u8 val) +{ + u32 reg; + + reg = sdhci_readl(host, SDHCI_TEGRA_VENDOR_CAP_OVERRIDES); + reg &= ~SDHCI_TEGRA_CAP_OVERRIDES_DQS_TRIM_MASK; + reg |= val<<SDHCI_TEGRA_CAP_OVERRIDES_DQS_TRIM_SHIFT; + sdhci_writel(host, reg, SDHCI_TEGRA_VENDOR_CAP_OVERRIDES); +}
Nit: I dislike using "reg" as a variable representing a register value because I keep interpreting it as designating a register offset. Hence I tend to use more explicit "offset" for actual register offsets and "value" for register values. But maybe that's just me. Thierry
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