Some controllers have 2 clock sources instead of 1. The 2nd clock is for the internal card detect logic and must be enabled/disabled along with the main core clock for proper operation.
Signed-off-by: Chris Brandt <[email protected]> --- v5: * call clk_disable_unprepare even if clk_cd is NULL v4: * add technical explanation within probe routine v3: * add more clarification to the commit log v2: * changed clk2 to clk_cd * disable clk if clk_cd enable fails * changed clock name from "carddetect" to "cd" --- drivers/mmc/host/sh_mobile_sdhi.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/drivers/mmc/host/sh_mobile_sdhi.c b/drivers/mmc/host/sh_mobile_sdhi.c index 59db14b..d964a0d 100644 --- a/drivers/mmc/host/sh_mobile_sdhi.c +++ b/drivers/mmc/host/sh_mobile_sdhi.c @@ -143,6 +143,7 @@ MODULE_DEVICE_TABLE(of, sh_mobile_sdhi_of_match); struct sh_mobile_sdhi { struct clk *clk; + struct clk *clk_cd; struct tmio_mmc_data mmc_data; struct tmio_mmc_dma dma_priv; struct pinctrl *pinctrl; @@ -190,6 +191,12 @@ static int sh_mobile_sdhi_clk_enable(struct tmio_mmc_host *host) if (ret < 0) return ret; + ret = clk_prepare_enable(priv->clk_cd); + if (ret < 0) { + clk_disable_unprepare(priv->clk); + return ret; + } + /* * The clock driver may not know what maximum frequency * actually works, so it should be set with the max-frequency @@ -255,6 +262,7 @@ static void sh_mobile_sdhi_clk_disable(struct tmio_mmc_host *host) struct sh_mobile_sdhi *priv = host_to_priv(host); clk_disable_unprepare(priv->clk); + clk_disable_unprepare(priv->clk_cd); } static int sh_mobile_sdhi_card_busy(struct mmc_host *mmc) @@ -572,6 +580,21 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev) goto eprobe; } + /* + * Some controllers provide a 2nd clock just to run the internal card + * detection logic. Unfortunately, the existing driver architecture does + * not support a separation of clocks for runtime PM usage. When + * native hotplug is used, the tmio driver assumes that the core + * must continue to run for card detect to stay active, so we cannot + * disable it. + * Additionally, it is prohibited to supply a clock to the core but not + * to the card detect circuit. That leaves us with if separate clocks + * are presented, we must treat them both as virtually 1 clock. + */ + priv->clk_cd = devm_clk_get(&pdev->dev, "cd"); + if (IS_ERR(priv->clk_cd)) + priv->clk_cd = NULL; + priv->pinctrl = devm_pinctrl_get(&pdev->dev); if (!IS_ERR(priv->pinctrl)) { priv->pins_default = pinctrl_lookup_state(priv->pinctrl, -- 2.10.1
