2021-08-16 07:41:16

by Mason Zhang

Subject: [PATCH 1/1] mmc: mediatek: fixed clk contrl flow

this patch fixed clk contrl flow in set clk rate, no need close clk src,
gate cg is enough, so no need call clk prepare/unprepare.

Signed-off-by: Mason Zhang <[email protected]>
---
drivers/mmc/host/mtk-sd.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index 4dfc246c5f95..d9835b272c1f 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -895,9 +895,9 @@ static void msdc_set_mclk(struct msdc_host *host, unsigned char timing, u32 hz)
* So if want to only gate src_clk, need gate its parent(mux).
*/
if (host->src_clk_cg)
- clk_disable_unprepare(host->src_clk_cg);
+ clk_disable(host->src_clk_cg);
else
- clk_disable_unprepare(clk_get_parent(host->src_clk));
+ clk_disable(clk_get_parent(host->src_clk));
if (host->dev_comp->clk_div_bits == 8)
sdr_set_field(host->base + MSDC_CFG,
MSDC_CFG_CKMOD | MSDC_CFG_CKDIV,
@@ -907,9 +907,9 @@ static void msdc_set_mclk(struct msdc_host *host, unsigned char timing, u32 hz)
MSDC_CFG_CKMOD_EXTRA | MSDC_CFG_CKDIV_EXTRA,
(mode << 12) | div);
if (host->src_clk_cg)
- clk_prepare_enable(host->src_clk_cg);
+ clk_enable(host->src_clk_cg);
else
- clk_prepare_enable(clk_get_parent(host->src_clk));
+ clk_enable(clk_get_parent(host->src_clk));

while (!(readl(host->base + MSDC_CFG) & MSDC_CFG_CKSTB))
cpu_relax();
--
2.18.0

2021-08-24 13:18:15

by Ulf Hansson

Subject: Re: [PATCH 1/1] mmc: mediatek: fixed clk contrl flow

On Mon, 16 Aug 2021 at 09:39, Mason Zhang <[email protected]> wrote:
>
> this patch fixed clk contrl flow in set clk rate, no need close clk src,
> gate cg is enough, so no need call clk prepare/unprepare.

No, this isn't the way we should deploy clock support in drivers.

If the driver doesn't need to gate/ungate clocks from atomic context,
the proper thing is to use the slow path APIs, clk_prepare_enable()
and clk_disable_unprepare().

Kind regards
Uffe

>
> Signed-off-by: Mason Zhang <[email protected]>
> ---
> drivers/mmc/host/mtk-sd.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 4dfc246c5f95..d9835b272c1f 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -895,9 +895,9 @@ static void msdc_set_mclk(struct msdc_host *host, unsigned char timing, u32 hz)
> * So if want to only gate src_clk, need gate its parent(mux).
> */
> if (host->src_clk_cg)
> - clk_disable_unprepare(host->src_clk_cg);
> + clk_disable(host->src_clk_cg);
> else
> - clk_disable_unprepare(clk_get_parent(host->src_clk));
> + clk_disable(clk_get_parent(host->src_clk));
> if (host->dev_comp->clk_div_bits == 8)
> sdr_set_field(host->base + MSDC_CFG,
> MSDC_CFG_CKMOD | MSDC_CFG_CKDIV,
> @@ -907,9 +907,9 @@ static void msdc_set_mclk(struct msdc_host *host, unsigned char timing, u32 hz)
> MSDC_CFG_CKMOD_EXTRA | MSDC_CFG_CKDIV_EXTRA,
> (mode << 12) | div);
> if (host->src_clk_cg)
> - clk_prepare_enable(host->src_clk_cg);
> + clk_enable(host->src_clk_cg);
> else
> - clk_prepare_enable(clk_get_parent(host->src_clk));
> + clk_enable(clk_get_parent(host->src_clk));
>
> while (!(readl(host->base + MSDC_CFG) & MSDC_CFG_CKSTB))
> cpu_relax();
> --
> 2.18.0
>