Re: [PATCH v2] clk: rockchip: reset init state before mmc card initialization

Shawn Lin
2015-09-03T23:49:19Z

在 2015/9/4 3:07, Heiko Stuebner 写道:
> Am Dienstag, 25. August 2015, 08:34:36 schrieb Shawn Lin:
>> mmc host controller's IO input/output timing is unpredictable if
>> bootloader execute tuning for HS200 mode. It might make kernel failed
>> to initialize mmc card in identification mode. The root cause is
>> tuning phase and degree setting for HS200 mode in bootloader aren't
>> applicable to that of identification mode in kernel stage. Anyway, we
>> can't force all bootloaders to reset tuning phase and degree setting
>> before into kernel. Simply reset it in rockchip_clk_register_mmc.
>>
>> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
>
> I'm not 100% sure why you need the new function instead of having that
> directly in rockchip_clk_register_mmc, but I guess that is a matter of taste

Thanks, Heiko.
:) That's indeed my taste but might not be appropriate sometimes. Also
add it directly into rockchip_clk_register_mmc looks fine to me.

I'm prone to do it as your advice since it can reduce a function call.

> and I don't have a hard opinion on that, so
>
> Reviewed-by: Heiko Stuebner <heiko@sntech.de>
>
>>
>> ---
>>
>> Changes in v2:
>> - rename to rockchip_clk_mmc_reset
>> - simplifying the code
>>
>> drivers/clk/rockchip/clk-mmc-phase.c | 16 ++++++++++++++++
>> 1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/clk/rockchip/clk-mmc-phase.c
>> b/drivers/clk/rockchip/clk-mmc-phase.c index e9f8df32..1d3e8fe6 100644
>> --- a/drivers/clk/rockchip/clk-mmc-phase.c
>> +++ b/drivers/clk/rockchip/clk-mmc-phase.c
>> @@ -38,6 +38,8 @@ static unsigned long rockchip_mmc_recalc(struct clk_hw
>> *hw, #define ROCKCHIP_MMC_DEGREE_MASK 0x3
>> #define ROCKCHIP_MMC_DELAYNUM_OFFSET 2
>> #define ROCKCHIP_MMC_DELAYNUM_MASK (0xff << ROCKCHIP_MMC_DELAYNUM_OFFSET)
>> +#define ROCKCHIP_MMC_INIT_STATE_RESET 0x1
>> +#define ROCKCHIP_MMC_INIT_STATE_SHIFT 1
>>
>> #define PSECS_PER_SEC 1000000000000LL
>>
>> @@ -119,6 +121,14 @@ static const struct clk_ops rockchip_mmc_clk_ops = {
>> .set_phase = rockchip_mmc_set_phase,
>> };
>>
>> +static void rockchip_clk_mmc_reset(struct rockchip_mmc_clock *mmc_clock)
>> +{
>> + if (mmc_clock->shift == ROCKCHIP_MMC_INIT_STATE_SHIFT)
>> + writel(HIWORD_UPDATE(ROCKCHIP_MMC_INIT_STATE_RESET,
>> + ROCKCHIP_MMC_INIT_STATE_RESET,
>> + mmc_clock->shift), mmc_clock->reg);
>> +}
>> +
>> struct clk *rockchip_clk_register_mmc(const char *name,
>> const char *const *parent_names, u8 num_parents,
>> void __iomem *reg, int shift)
>> @@ -139,6 +149,12 @@ struct clk *rockchip_clk_register_mmc(const char *name,
>> mmc_clock->reg = reg;
>> mmc_clock->shift = shift;
>>
>> + /*
>> + * Assert init_state to soft reset the CLKGEN
>> + * for mmc tuning phase and degree
>> + */
>> + rockchip_clk_mmc_reset(mmc_clock);
>> +
>> if (name)
>> init.name = name;
>
>
>
>

--
Best Regards
Shawn Lin