From: Matthias Kaehlcke <mka@chromium.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Bjorn Andersson <andersson@kernel.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
swboyd@chromium.org, linux-arm-msm@vger.kernel.org,
linux-input@vger.kernel.org,
Yunlong Jia <ecs.beijing2022@gmail.com>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
Andy Gross <agross@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/5] arm64: dts: qcom: sc7180: Bump up trogdor ts_reset_l drive strength
Date: Thu, 8 Dec 2022 23:22:07 +0000 [thread overview]
Message-ID: <Y5Jxn01EzEZ8fE1G@google.com> (raw)
In-Reply-To: <20221208111910.1.I39c387f1e3176fcf340039ec12d54047de9f8526@changeid>
On Thu, Dec 08, 2022 at 11:20:02AM -0800, Douglas Anderson wrote:
> On at least one board (pazquel360) the reset line for the touchscreen
> was scoped and found to take almost 2 ms to fall when we drove it
> low. This wasn't great because the Linux driver for the touchscreen
> (the elants_i2c driver) thinks it can do a 500 us reset pulse. If we
> bump the drive strength to 8 mA then the reset line went down in ~421
> us.
>
> NOTE: we could apply this fix just for pazquel360, but:
> * Probably other trogdor devices have similar timings and it's just
> that nobody has noticed it before.
> * There are other trogdor boards using the same elan driver that tries
> to do 500 us reset pulses.
> * Bumping the drive strength to 8mA across the board won't hurt. This
> isn't a high speed signal or anything.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
next prev parent reply other threads:[~2022-12-08 23:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-08 19:20 [PATCH 0/5] arm64: dts: qcom: sc7180: Make pazquel360's touchscreen work Douglas Anderson
2022-12-08 19:20 ` [PATCH 1/5] arm64: dts: qcom: sc7180: Bump up trogdor ts_reset_l drive strength Douglas Anderson
2022-12-08 23:22 ` Matthias Kaehlcke [this message]
2022-12-08 19:20 ` [PATCH 2/5] arm64: dts: qcom: sc7180: Add trogdor eDP/touchscreen regulator off-on-time Douglas Anderson
2022-12-08 23:31 ` Matthias Kaehlcke
2022-12-08 19:20 ` [PATCH 3/5] arm64: dts: qcom: sc7180: Start the trogdor eDP/touchscreen regulator on Douglas Anderson
2022-12-08 23:33 ` Matthias Kaehlcke
2022-12-08 19:20 ` [PATCH 4/5] arm64: dts: qcom: sc7180: Add pazquel360 touschreen Douglas Anderson
2022-12-08 23:36 ` Matthias Kaehlcke
2022-12-08 19:20 ` [PATCH 5/5] Input: elants_i2c: Delay longer with reset asserted Douglas Anderson
2022-12-08 23:39 ` Matthias Kaehlcke
2022-12-09 1:38 ` Dmitry Torokhov
2022-12-09 1:48 ` Dmitry Torokhov
2022-12-09 1:49 ` Doug Anderson
2022-12-09 1:41 ` kernel test robot
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