From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Matthias Kaehlcke <mka@chromium.org>
Cc: Andy Gross <andy.gross@linaro.org>,
David Brown <david.brown@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
Balakrishna Godavarthi <bgodavar@codeaurora.org>
Subject: Re: [PATCH] arm64: dts: qcom: sdm845-mtp: Add WCN3990 BT node
Date: Thu, 17 Jan 2019 13:55:59 -0800 [thread overview]
Message-ID: <20190117215559.GC12955@builder> (raw)
In-Reply-To: <20190117192812.GV261387@google.com>
On Thu 17 Jan 11:28 PST 2019, Matthias Kaehlcke wrote:
> On Wed, Jan 16, 2019 at 08:40:06PM -0800, Bjorn Andersson wrote:
[..]
> > +&qup_uart6_default {
> > + pinmux {
> > + pins = "gpio45", "gpio46", "gpio47", "gpio48";
> > + function = "qup6";
> > + };
> > +
> > + ctsrx {
> > + pins = "gpio45", "gpio48";
> > + drive-strength = <2>;
>
> CTS and RX are input signals, no need to configure drive strength in
> this case IIUC.
>
Right, didn't think that far when I hacked this up.
> > + bias-no-pull;
>
> On another SDM845 based device we observe garbage on RX at
> initialization time, unless we enable a pull-up.
>
> > + };
> > +
> > + rts {
> > + pins = "gpio46";
> > + drive-strength = <2>;
> > + bias-pull-down;
> > + };
>
> On our device we don't configure a pull on the lines driven by the
> AP. I think a pull-down on RTS should be fine though since it matches
> the pull (during reset) on CTS of the BT module.
>
> > + tx {
> > + pins = "gpio47";
> > + drive-strength = <2>;
> > + bias-pull-up;
> > + };
> > +};
>
> Similar to RTS, the pull matches the one on RXD of the BT module.
>
> For reference, this is what we currently use on our device:
>
> https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1391888/3/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi
>
Thanks, I will update the patch.
Regards,
Bjorn
prev parent reply other threads:[~2019-01-17 21:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-17 4:40 [PATCH] arm64: dts: qcom: sdm845-mtp: Add WCN3990 BT node Bjorn Andersson
2019-01-17 6:10 ` Balakrishna Godavarthi
2019-01-17 21:53 ` Bjorn Andersson
2019-01-17 19:28 ` Matthias Kaehlcke
2019-01-17 21:55 ` Bjorn Andersson [this message]
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