From: BurningHoryd <sjunhyuk1@gmail.com>
To: Neil Armstrong <neil.armstrong@linaro.org>,
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org,
Vinod Koul <vkoul@kernel.org>,
Abhinav Kumar <quic_abhinavk@quicinc.com>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>
Subject: Re: SM8250 USB-C DP alt mode: DP AUX times out in reversed (CC2) cable orientation
Date: Mon, 7 Sep 2026 14:13:25 -0400 [thread overview]
Message-ID: <20260907181325.89746-1-sjunhyuk1@gmail.com> (raw)
In-Reply-To: <e1971874-6e06-4ffb-8118-c4acc40144eb@linaro.org>
On 9/7/26 18:35, Neil Armstrong wrote:
> Yes if it's a discrete SBU mux, gpio-sbu-mux was designed for that, and
> keep the nb7vpq904m and just drop the SBU link to the redriver and replace
> it with a link to the SBU mux instead.
That fixed it. A gpio-sbu-mux node on TLMM 8 (select) / TLMM 9 (enable),
the connector's SBU graph endpoint moved from the nb7vpq904m to it, and
the nb7vpq904m's enable-gpios dropped (TLMM 9 is the mux enable, not the
redriver enable). nb7vpq904m stays as the SS retimer-switch.
Reversed orientation now brings DP up reliably - one normal plug and
three reversed re-plugs, all four train to 4 lanes and stay connected,
no more DPCD read timeout. Normal orientation is unchanged.
This board (Retroid Pocket 5) isn't upstream yet, so the fix lands
downstream for now, but thanks a lot for the quick pointer - "nb7vpq904m
alone doesn't switch SBU" was exactly the piece I was missing.
BurningHoryd
--
linux-phy mailing list
linux-phy@lists.infradead.org
https://lists.infradead.org/mailman/listinfo/linux-phy
prev parent reply other threads:[~2026-09-07 18:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-06 22:52 SM8250 USB-C DP alt mode: DP AUX times out in reversed (CC2) cable orientation BurningHoryd
2026-09-07 6:40 ` Neil Armstrong
2026-09-07 16:26 ` BurningHoryd
2026-09-07 16:35 ` Neil Armstrong
2026-09-07 18:13 ` BurningHoryd [this message]
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