As per the current implementation, after FSC (Full Scale Current)
and brightness update the sync bits are transitioned from set-then-clear.
But, the FSC and brightness sync takes place during a clear-then-set
transition of the sync bits. So the hardware team recommends a
clear-then-set approach in order to guarantee such a transition
regardless of the previous register state.
Signed-off-by: Kiran Gunda <[email protected]>
---
drivers/video/backlight/qcom-wled.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index aef52b9..19f83ac 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -337,13 +337,13 @@ static int wled3_sync_toggle(struct wled *wled)
rc = regmap_update_bits(wled->regmap,
wled->ctrl_addr + WLED3_SINK_REG_SYNC,
- mask, mask);
+ mask, WLED3_SINK_REG_SYNC_CLEAR);
if (rc < 0)
return rc;
rc = regmap_update_bits(wled->regmap,
wled->ctrl_addr + WLED3_SINK_REG_SYNC,
- mask, WLED3_SINK_REG_SYNC_CLEAR);
+ mask, mask);
return rc;
}
@@ -353,17 +353,17 @@ static int wled5_mod_sync_toggle(struct wled *wled)
int rc;
u8 val;
- val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
- WLED5_SINK_REG_SYNC_MOD_B_BIT;
rc = regmap_update_bits(wled->regmap,
wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
- WLED5_SINK_REG_SYNC_MASK, val);
+ WLED5_SINK_REG_SYNC_MASK, 0);
if (rc < 0)
return rc;
+ val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
+ WLED5_SINK_REG_SYNC_MOD_B_BIT;
return regmap_update_bits(wled->regmap,
wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
- WLED5_SINK_REG_SYNC_MASK, 0);
+ WLED5_SINK_REG_SYNC_MASK, val);
}
static int wled_ovp_fault_status(struct wled *wled, bool *fault_set)
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
On 2021-03-01 15:32, Daniel Thompson wrote:
> On Mon, Mar 01, 2021 at 02:58:36PM +0530, Kiran Gunda wrote:
>> As per the current implementation, after FSC (Full Scale Current)
>> and brightness update the sync bits are transitioned from
>> set-then-clear.
>
> This does not makes sense since there are too many verbs. Set and clear
> are both verbs so in this context: "the code will set the bit and then
> the code will clear the bit".
>
> Either:
>
> s/transitioned from set-then-clear/set-then-cleared/.
>
> Or:
>
> s/transitioned from set-then-clear/using a set-then-clear approach/.
>
>> But, the FSC and brightness sync takes place during a clear-then-set
>> transition of the sync bits.
>
> Likewise this no longer makes sense and had also become misleading.
> Two changes of state, clear and then set, do not usually result in a
> single transition.
>
> Either:
>
> s/clear-then-set/0 to 1/
>
> Alternatively, if you want to stick exclusively to the set/clear
> terminology then replace the whole quoted section with:
>
> But, the FSC and brightness sync takes place when the sync bits are
> set (e.g. on a rising edge).
>
>
>> So the hardware team recommends a
>> clear-then-set approach in order to guarantee such a transition
>> regardless of the previous register state.
>>
>> Signed-off-by: Kiran Gunda <[email protected]>
>
> With one of each of the changes proposed above:
> Reviewed-by: Daniel Thompson <[email protected]>
>
>
> Daniel.
>
Apologies for the mistake. I have corrected and submitted the
V4 series with the "reviewed-by" tag.
>
>> ---
>> drivers/video/backlight/qcom-wled.c | 12 ++++++------
>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/video/backlight/qcom-wled.c
>> b/drivers/video/backlight/qcom-wled.c
>> index aef52b9..19f83ac 100644
>> --- a/drivers/video/backlight/qcom-wled.c
>> +++ b/drivers/video/backlight/qcom-wled.c
>> @@ -337,13 +337,13 @@ static int wled3_sync_toggle(struct wled *wled)
>>
>> rc = regmap_update_bits(wled->regmap,
>> wled->ctrl_addr + WLED3_SINK_REG_SYNC,
>> - mask, mask);
>> + mask, WLED3_SINK_REG_SYNC_CLEAR);
>> if (rc < 0)
>> return rc;
>>
>> rc = regmap_update_bits(wled->regmap,
>> wled->ctrl_addr + WLED3_SINK_REG_SYNC,
>> - mask, WLED3_SINK_REG_SYNC_CLEAR);
>> + mask, mask);
>>
>> return rc;
>> }
>> @@ -353,17 +353,17 @@ static int wled5_mod_sync_toggle(struct wled
>> *wled)
>> int rc;
>> u8 val;
>>
>> - val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
>> - WLED5_SINK_REG_SYNC_MOD_B_BIT;
>> rc = regmap_update_bits(wled->regmap,
>> wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
>> - WLED5_SINK_REG_SYNC_MASK, val);
>> + WLED5_SINK_REG_SYNC_MASK, 0);
>> if (rc < 0)
>> return rc;
>>
>> + val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
>> + WLED5_SINK_REG_SYNC_MOD_B_BIT;
>> return regmap_update_bits(wled->regmap,
>> wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
>> - WLED5_SINK_REG_SYNC_MASK, 0);
>> + WLED5_SINK_REG_SYNC_MASK, val);
>> }
>>
>> static int wled_ovp_fault_status(struct wled *wled, bool *fault_set)
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
>> Forum,
>> a Linux Foundation Collaborative Project
>>
On Mon, Mar 01, 2021 at 02:58:36PM +0530, Kiran Gunda wrote:
> As per the current implementation, after FSC (Full Scale Current)
> and brightness update the sync bits are transitioned from set-then-clear.
This does not makes sense since there are too many verbs. Set and clear
are both verbs so in this context: "the code will set the bit and then
the code will clear the bit".
Either:
s/transitioned from set-then-clear/set-then-cleared/.
Or:
s/transitioned from set-then-clear/using a set-then-clear approach/.
> But, the FSC and brightness sync takes place during a clear-then-set
> transition of the sync bits.
Likewise this no longer makes sense and had also become misleading.
Two changes of state, clear and then set, do not usually result in a
single transition.
Either:
s/clear-then-set/0 to 1/
Alternatively, if you want to stick exclusively to the set/clear
terminology then replace the whole quoted section with:
But, the FSC and brightness sync takes place when the sync bits are
set (e.g. on a rising edge).
> So the hardware team recommends a
> clear-then-set approach in order to guarantee such a transition
> regardless of the previous register state.
>
> Signed-off-by: Kiran Gunda <[email protected]>
With one of each of the changes proposed above:
Reviewed-by: Daniel Thompson <[email protected]>
Daniel.
> ---
> drivers/video/backlight/qcom-wled.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
> index aef52b9..19f83ac 100644
> --- a/drivers/video/backlight/qcom-wled.c
> +++ b/drivers/video/backlight/qcom-wled.c
> @@ -337,13 +337,13 @@ static int wled3_sync_toggle(struct wled *wled)
>
> rc = regmap_update_bits(wled->regmap,
> wled->ctrl_addr + WLED3_SINK_REG_SYNC,
> - mask, mask);
> + mask, WLED3_SINK_REG_SYNC_CLEAR);
> if (rc < 0)
> return rc;
>
> rc = regmap_update_bits(wled->regmap,
> wled->ctrl_addr + WLED3_SINK_REG_SYNC,
> - mask, WLED3_SINK_REG_SYNC_CLEAR);
> + mask, mask);
>
> return rc;
> }
> @@ -353,17 +353,17 @@ static int wled5_mod_sync_toggle(struct wled *wled)
> int rc;
> u8 val;
>
> - val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
> - WLED5_SINK_REG_SYNC_MOD_B_BIT;
> rc = regmap_update_bits(wled->regmap,
> wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
> - WLED5_SINK_REG_SYNC_MASK, val);
> + WLED5_SINK_REG_SYNC_MASK, 0);
> if (rc < 0)
> return rc;
>
> + val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
> + WLED5_SINK_REG_SYNC_MOD_B_BIT;
> return regmap_update_bits(wled->regmap,
> wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
> - WLED5_SINK_REG_SYNC_MASK, 0);
> + WLED5_SINK_REG_SYNC_MASK, val);
> }
>
> static int wled_ovp_fault_status(struct wled *wled, bool *fault_set)
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>