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Mon, 30 Mar 2026 17:10:15 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1774883431; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=p1MeQWrS6eGeRuRaT9b0wX2w36pWQDDzuAhBPQ3PoRQ=; b=MXg8UvK8KWtJw7KB3Rap3NGvp1/8bEh+95uH9XyT2Di0JupAl1bF/aIQADEyMy2qElkrTB ODmctauWYW8JMtSu3vWYwV22bNPtCN0WcLP6vs5HaozqoLlZayxN3vu2UfOVkdCyldTFxl C8ZwyzAbV+VIN50/Wc6ddFc0haY1pWQGzeX1AGsdb8BqEBJ/Mi+zDmwydGS4smiEdXIizE Z7Wuxs0lWOb49XE5riMNWwFldiv6uDfizpWrsO3dkhaiBl/Rt3wkxKqvTG1WNbpeCvnpYw nYxD+pcPlsmFJ/kGWG9wl19T5zbryW3eKyl/g+l6pzKdvyYudDG9qKeU3OuSCw== Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 30 Mar 2026 17:10:14 +0200 Message-Id: From: "Luca Ceresoli" Subject: Re: [PATCH 4/8] drm/bridge: dw-hdmi: document the output_port field Cc: "Kory Maincent (TI.com)" , =?utf-8?q?Herv=C3=A9_Codina?= , "Hui Pu" , "Ian Ray" , "Thomas Petazzoni" , , , , , , "Adam Ford" , "Alexander Stein" , "Anson Huang" , "Christopher Obbard" , "Daniel Scally" , "Emanuele Ghidoli" , "Fabio Estevam" , "Francesco Dolcini" , "Frieder Schrempf" , "Gilles Talis" , =?utf-8?q?Goran_Ra=C4=91enovi=C4=87?= , "Heiko Schocher" , "Joao Paulo Goncalves" , "Josua Mayer" , "Kieran Bingham" , "Marco Felsch" , "Martyn Welch" , "Oleksij Rempel" , "Peng Fan" , "Philippe Schenker" , "Richard Hu" , "Shengjiu Wang" , "Stefan Eichenberger" , "Vitor Soares" To: "Damon Ding" , "Liu Ying" , "Marek Vasut" , "Stefan Agner" , "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "David Airlie" , "Simona Vetter" , "Frank Li" , "Sascha Hauer" , "Pengutronix Kernel Team" , "Fabio Estevam" , "Andrzej Hajda" , "Neil Armstrong" , "Robert Foss" , "Laurent Pinchart" , "Jonas Karlman" , "Jernej Skrabec" , "Rob Herring" , "Saravana Kannan" X-Mailer: aerc 0.20.1 References: <20260320-drm-lcdif-dbanc-v1-0-479a04133e70@bootlin.com> <20260320-drm-lcdif-dbanc-v1-4-479a04133e70@bootlin.com> <050c6532-8122-4ded-9946-3ce1a86d2be0@nxp.com> <4396e94d-7b88-4599-a938-3c1932a2f9cb@rock-chips.com> In-Reply-To: <4396e94d-7b88-4599-a938-3c1932a2f9cb@rock-chips.com> X-Last-TLS-Session-Version: TLSv1.3 Hello Damon, On Mon Mar 30, 2026 at 3:13 AM CEST, Damon Ding wrote: >>>>> diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdm= i.h >>>>> index 336f062e1f9d..45f6ba1a8ee1 100644 >>>>> --- a/include/drm/bridge/dw_hdmi.h >>>>> +++ b/include/drm/bridge/dw_hdmi.h >>>>> @@ -126,6 +126,11 @@ struct dw_hdmi_phy_ops { >>>>> struct dw_hdmi_plat_data { >>>>> struct regmap *regm; >>>>> >>>>> + /* >>>>> + * The HDMI output port number (which must be 1) if it is described >>>> >>>> I'd rephrase: >>>> The HDMI output port number must be 1 ... >>>> >>> >>> Yes, the output port number should be 1, but I found that the output >>> port number in the Rockchip-side dw-hdmi driver remains 0. >> >> Really? I checked all the bindings in >> Documentation/devicetree/bindings/display/rockchip/*hdmi* and all mentio= n >> port@1 as the output port number. Can you point to code using port@0 as = the >> output port? >> >> Should it be true, that would be unfortunate because the output_port >> variable does not handle this case. It's used as a sort of bool-or-int >> variable: >> >> * as a bool [0] to find out whether the DT is supposed to describe the >> output port >> * as an integer to tell the port number to parse in DT [1] >> >> So saying "please parse port 0" is impossible. >> >> [0] https://elixir.bootlin.com/linux/v7.0-rc5/source/drivers/gpu/drm/bri= dge/synopsys/dw-hdmi.c#L3310 >> [1] https://elixir.bootlin.com/linux/v7.0-rc5/source/drivers/gpu/drm/bri= dge/synopsys/dw-hdmi.c#L3315 >> > > Aha, my description might be a little misleading. The > &dw_hdmi_plat_data.output_port is 0 on the Rockchip side, so the next > bridge will not be parsed for it. > > Then I think the &dw_hdmi_plat_data.output_port should be 1, as this > helps support the hdmi-connector and other bridge chips. Ah, OK, that's all clear now. > BTW: The Rockchip side dw-hdmi patches for bridge connector support will > be updated as a follow-up to your patch series. :-) Great! Don't forget to Cc me. Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com