Heiko,
On Sat, Jun 18, 2016 at 5:20 AM, Heiko Stübner <heiko@xxxxxxxxx> wrote:
> Am Montag, 13. Juni 2016, 16:04:34 schrieb Douglas Anderson:
>> The "phyctrl_frqsel" is described in the Arasan datasheet [1] as "the
>> frequency range of DLL operation". Although the Rockchip variant of
>> this PHY has different ranges than the reference Arasan PHY it appears
>> as if the functionality is similar. We should set this phyctrl field
>> properly.
>>
>> Note: as per Rockchip engineers, apparently the "phyctrl_frqsel" is
>> actually only useful in HS200 / HS400 modes even though the DLL itself
>> it used for some purposes in all modes. See the discussion in the
>> earlier change in this series: ("mmc: sdhci-of-arasan: Always power the
>> PHY off/on when clock changes"). In any case, it shouldn't hurt to set
>> this always.
>>
>> Note that this change should allow boards to run at HS200 / HS400 speed
>> modes while running at 100 MHz or 150 MHz. In fact, running HS400 at
>> 150 MHz (giving 300 MB/s) is the main motivation of this series, since
>> performance is still good but signal integrity problems are less
>> prevelant at 150 MHz.
>>
>> [1]: https://arasan.com/wp-content/media/eMMC-5-1-Total-Solution_Rev-1-3.pdf
>>
>> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
>> ---
>> Changes in v2:
>> - Warn if we're more than 15 MHz from ideal rate (Shawn)
>> - Move code cleanup before set phyctrl_frqsel based on card clock (Shawn)
>> - Fix typo USB => SDHCI (Shawn)
>>
>> drivers/phy/phy-rockchip-emmc.c | 82
>> ++++++++++++++++++++++++++++++++++------- 1 file changed, 69 insertions(+),
>> 13 deletions(-)
>>
>> diff --git a/drivers/phy/phy-rockchip-emmc.c
>> b/drivers/phy/phy-rockchip-emmc.c index 23fe50864526..51ddd543fd04 100644
>> --- a/drivers/phy/phy-rockchip-emmc.c
>> +++ b/drivers/phy/phy-rockchip-emmc.c
>> @@ -14,6 +14,7 @@
>> * GNU General Public License for more details.
>> */
>>
>> +#include <linux/clk.h>
>> #include <linux/delay.h>
>> #include <linux/mfd/syscon.h>
>> #include <linux/module.h>
>> @@ -78,16 +79,73 @@
>> struct rockchip_emmc_phy {
>> unsigned int reg_offset;
>> struct regmap *reg_base;
>> + struct clk *emmcclk;
>> };
>>
>> -static int rockchip_emmc_phy_power(struct rockchip_emmc_phy *rk_phy,
>> - bool on_off)
>> +static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
>> {
>> + struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>> unsigned int caldone;
>> unsigned int dllrdy;
>> + unsigned int freqsel = PHYCTRL_FREQSEL_200M;
>> unsigned long timeout;
>>
>> /*
>> + * We purposely get the clock here and not in probe to avoid the
>> + * circular dependency problem. We expect:
>> + * - PHY driver to probe
>> + * - SDHCI driver to start probe
>> + * - SDHCI driver to register it's clock
>> + * - SDHCI driver to get the PHY
>> + * - SDHCI driver to power on the PHY
>> + */
>
> Doesn't that leave open the unbind / removal case with that same circular
> dependency? While true that the clock-framework does some special handling on
> clk_unregister, I don't think this would catch multiple unbind/bind actions.
>
> The emmc-phy would still hold on to the old clock-instance with the empty clk-
> ops the ccf assigns, even when the rebind of the arasan-sdhci would create a
> new clock.
>
> How about using phy-init / phy-exit callbacks for that instead? (Aka clk_get
> and clk_put the emmc clock in there instead of using the devm variant)
Using phy-init and phy-exit is perfect. I'll spin shortly.
>> + if (!rk_phy->emmcclk) {
>> + rk_phy->emmcclk = devm_clk_get(&phy->dev, "emmcclk");
>> +
>> + /* Don't expect defer at this point; try next time */
>> + if (PTR_ERR(rk_phy->emmcclk) == -EPROBE_DEFER) {
>> + dev_warn(&phy->dev, "Unexpected emmcclk defer\n");
>> + rk_phy->emmcclk = NULL;
>> + }
>> + }
>> +
>> + if (!IS_ERR_OR_NULL(rk_phy->emmcclk)) {
>
> you just made it NULL in the error case above?
Yeah. The idea was the if we happened to get a EPROBE_DEFER (should
never happen) we would continue on and just skip this part. In any
case, should be a moot point with the new version, which I'll send out
soon.
-Doug
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