From: Quanyang Wang <[email protected]>
If there is a IOCTL_SET_PLL_FRAC_MODE request sent to ATF ever,
we shouldn't skip invoking PM_CLOCK_ENABLE fn even though this
pll has been enabled. In ATF implementation, it will only assign
the mode to the variable (struct pm_pll *)pll->mode when handling
IOCTL_SET_PLL_FRAC_MODE call. Invoking PM_CLOCK_ENABLE can force
ATF send request to PWU to set the pll mode to PLL's register.
There is a scenario that happens in enabling VPLL_INT(clk_id:96):
1) VPLL_INT has been enabled during booting.
2) A driver calls clk_set_rate and according to the rate, the VPLL_INT
should be set to FRAC mode. Then zynqmp_pll_set_mode is called
to pass IOCTL_SET_PLL_FRAC_MODE to ATF. Note that at this point
ATF just stores the mode to a variable.
3) This driver calls clk_prepare_enable and zynqmp_pll_enable is
called to try to enable VPLL_INT pll. Because of 1), the function
zynqmp_pll_enable just returns without doing anything after checking
that this pll has been enabled.
In the scenario above, the pll mode of VPLL_INT will never be set
successfully. So adding set_pll_mode to check condition to fix it.
Signed-off-by: Quanyang Wang <[email protected]>
Tested-by: Laurent Pinchart <[email protected]>
---
V2:
- add Tested-by tag, thanks Laurent.
- fix typos in commit message and multiline code comments
---
drivers/clk/zynqmp/pll.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/zynqmp/pll.c b/drivers/clk/zynqmp/pll.c
index 92f449ed38e5..fa89ee722a6d 100644
--- a/drivers/clk/zynqmp/pll.c
+++ b/drivers/clk/zynqmp/pll.c
@@ -14,10 +14,12 @@
* struct zynqmp_pll - PLL clock
* @hw: Handle between common and hardware-specific interfaces
* @clk_id: PLL clock ID
+ * @set_pll_mode: Whether an IOCTL_SET_PLL_FRAC_MODE request be sent to ATF
*/
struct zynqmp_pll {
struct clk_hw hw;
u32 clk_id;
+ bool set_pll_mode;
};
#define to_zynqmp_pll(_hw) container_of(_hw, struct zynqmp_pll, hw)
@@ -81,6 +83,8 @@ static inline void zynqmp_pll_set_mode(struct clk_hw *hw, bool on)
if (ret)
pr_warn_once("%s() PLL set frac mode failed for %s, ret = %d\n",
__func__, clk_name, ret);
+ else
+ clk->set_pll_mode = true;
}
/**
@@ -240,9 +244,15 @@ static int zynqmp_pll_enable(struct clk_hw *hw)
u32 clk_id = clk->clk_id;
int ret;
- if (zynqmp_pll_is_enabled(hw))
+ /*
+ * Don't skip enabling clock if there is an IOCTL_SET_PLL_FRAC_MODE request
+ * that has been sent to ATF.
+ */
+ if (zynqmp_pll_is_enabled(hw) && (!clk->set_pll_mode))
return 0;
+ clk->set_pll_mode = false;
+
ret = zynqmp_pm_clock_enable(clk_id);
if (ret)
pr_warn_once("%s() clock enable failed for %s, ret = %d\n",
--
2.25.1
Quoting [email protected] (2021-03-30 05:17:01)
> From: Quanyang Wang <[email protected]>
>
> If there is a IOCTL_SET_PLL_FRAC_MODE request sent to ATF ever,
> we shouldn't skip invoking PM_CLOCK_ENABLE fn even though this
> pll has been enabled. In ATF implementation, it will only assign
> the mode to the variable (struct pm_pll *)pll->mode when handling
> IOCTL_SET_PLL_FRAC_MODE call. Invoking PM_CLOCK_ENABLE can force
> ATF send request to PWU to set the pll mode to PLL's register.
>
> There is a scenario that happens in enabling VPLL_INT(clk_id:96):
> 1) VPLL_INT has been enabled during booting.
> 2) A driver calls clk_set_rate and according to the rate, the VPLL_INT
> should be set to FRAC mode. Then zynqmp_pll_set_mode is called
> to pass IOCTL_SET_PLL_FRAC_MODE to ATF. Note that at this point
> ATF just stores the mode to a variable.
> 3) This driver calls clk_prepare_enable and zynqmp_pll_enable is
> called to try to enable VPLL_INT pll. Because of 1), the function
> zynqmp_pll_enable just returns without doing anything after checking
> that this pll has been enabled.
>
> In the scenario above, the pll mode of VPLL_INT will never be set
> successfully. So adding set_pll_mode to check condition to fix it.
>
> Signed-off-by: Quanyang Wang <[email protected]>
> Tested-by: Laurent Pinchart <[email protected]>
> ---
Any Fixes tag?
Hi Stephen,
On 4/1/21 9:49 AM, Stephen Boyd wrote:
> Quoting [email protected] (2021-03-30 05:17:01)
>> From: Quanyang Wang <[email protected]>
>>
>> If there is a IOCTL_SET_PLL_FRAC_MODE request sent to ATF ever,
>> we shouldn't skip invoking PM_CLOCK_ENABLE fn even though this
>> pll has been enabled. In ATF implementation, it will only assign
>> the mode to the variable (struct pm_pll *)pll->mode when handling
>> IOCTL_SET_PLL_FRAC_MODE call. Invoking PM_CLOCK_ENABLE can force
>> ATF send request to PWU to set the pll mode to PLL's register.
>>
>> There is a scenario that happens in enabling VPLL_INT(clk_id:96):
>> 1) VPLL_INT has been enabled during booting.
>> 2) A driver calls clk_set_rate and according to the rate, the VPLL_INT
>> should be set to FRAC mode. Then zynqmp_pll_set_mode is called
>> to pass IOCTL_SET_PLL_FRAC_MODE to ATF. Note that at this point
>> ATF just stores the mode to a variable.
>> 3) This driver calls clk_prepare_enable and zynqmp_pll_enable is
>> called to try to enable VPLL_INT pll. Because of 1), the function
>> zynqmp_pll_enable just returns without doing anything after checking
>> that this pll has been enabled.
>>
>> In the scenario above, the pll mode of VPLL_INT will never be set
>> successfully. So adding set_pll_mode to check condition to fix it.
>>
>> Signed-off-by: Quanyang Wang <[email protected]>
>> Tested-by: Laurent Pinchart <[email protected]>
>> ---
> Any Fixes tag?
Will add it at V3 patch.
Thanks,
Quanyang