From: kgunda@codeaurora.org
To: Daniel Thompson <daniel.thompson@linaro.org>
Cc: bjorn.andersson@linaro.org, jingoohan1@gmail.com,
lee.jones@linaro.org, b.zolnierkie@samsung.com,
dri-devel@lists.freedesktop.org, jacek.anaszewski@gmail.com,
pavel@ucw.cz, robh+dt@kernel.org, mark.rutland@arm.com,
linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, Andy Gross <agross@kernel.org>,
linux-arm-msm@vger.kernel.org, linux-fbdev@vger.kernel.org,
phone-devel@vger.kernel.org
Subject: Re: [PATCH V3 2/2] backlight: qcom-wled: Correct the sync_toggle sequence
Date: Mon, 01 Mar 2021 22:12:21 +0530 [thread overview]
Message-ID: <f25a2c8b1bf0eae63a2fe9a31c824f1e@codeaurora.org> (raw)
In-Reply-To: <20210301100239.orbt7km6lgjwvzii@maple.lan>
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 <kgunda@codeaurora.org>
>
> With one of each of the changes proposed above:
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
>
>
> 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
>>
prev parent reply other threads:[~2021-03-01 16:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1614590916-27070-1-git-send-email-kgunda@codeaurora.org>
2021-03-01 9:28 ` [PATCH V3 1/2] backlight: qcom-wled: Fix FSC update issue for WLED5 Kiran Gunda
2021-03-01 9:28 ` [PATCH V3 2/2] backlight: qcom-wled: Correct the sync_toggle sequence Kiran Gunda
2021-03-01 10:02 ` Daniel Thompson
2021-03-01 16:42 ` kgunda [this message]
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