From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fllvem-ot03.ext.ti.com (fllvem-ot03.ext.ti.com [198.47.19.245]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 26AAE1A8F79 for ; Fri, 13 Jun 2025 10:01:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.47.19.245 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749808903; cv=none; b=tM/jA/rHW28+uB9MCFu5M0EW/UUyUBa1uB9eSJWGuPCHqyEfInT6thCBsYzPl7LwnZsTO9oo1cLaDdFVAAlw9FFsW81QVszhAFWyH1CmyPp80OQpbjC4snw+QL472e1oJzievaPj23aBYKpi2YxlrKrieu6cVB1149ed3YTkPZ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749808903; c=relaxed/simple; bh=vdE8ZJvKezXZAkWqUAojLnlJRXRUgCIpmIhpemx4JtQ=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=tOrxDs5zqgg6LPkpQgZGsnK6vt0rEmHSjAPVcdTmJ/dNfPPJ7GNmT0VJfJoFGC/2fKtgYCTzsxXoB6OHHFkfAZC2QmUAKl994fjguesKnynAQH6myPGCkD0KdR22fOuRIE2rrD794g55eTUT/J75ch5mxH+yGXCfMboM8UArlzw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ti.com; spf=pass smtp.mailfrom=ti.com; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b=dWiB/kdq; arc=none smtp.client-ip=198.47.19.245 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ti.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ti.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="dWiB/kdq" Received: from lelvem-sh01.itg.ti.com ([10.180.77.71]) by fllvem-ot03.ext.ti.com (8.15.2/8.15.2) with ESMTP id 55DA15wA3104814; Fri, 13 Jun 2025 05:01:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1749808865; bh=UOuiWlX9p7lNVU0QfBFOh9XTcLaprri11iz8KEMFwho=; h=Date:Subject:To:CC:References:From:In-Reply-To; b=dWiB/kdqRYglvWY4MP9yXFY7QgkgOGDQQ+F/9kTNz4JJqX3vnFexfqz7P9j2j6bgR 9n2dVAANFS0BPDyGt8sSLebLejQV+6kECX9OgLRxSRdNwkXGYK9gN+2HqL2RxLJguW IRI0L+zZqVb8TGIvN26JCvuipReHMJmJHajsuZtY= Received: from DFLE109.ent.ti.com (dfle109.ent.ti.com [10.64.6.30]) by lelvem-sh01.itg.ti.com (8.18.1/8.18.1) with ESMTPS id 55DA14b13357680 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA256 bits=128 verify=FAIL); Fri, 13 Jun 2025 05:01:04 -0500 Received: from DFLE108.ent.ti.com (10.64.6.29) by DFLE109.ent.ti.com (10.64.6.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.55; Fri, 13 Jun 2025 05:01:04 -0500 Received: from lelvem-mr05.itg.ti.com (10.180.75.9) by DFLE108.ent.ti.com (10.64.6.29) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.55 via Frontend Transport; Fri, 13 Jun 2025 05:01:04 -0500 Received: from [172.24.227.14] (jayesh-hp-z2-tower-g5-workstation.dhcp.ti.com [172.24.227.14]) by lelvem-mr05.itg.ti.com (8.18.1/8.18.1) with ESMTP id 55DA0v3G3579539; Fri, 13 Jun 2025 05:00:58 -0500 Message-ID: <1301f0d9-7ebd-44c1-bfcf-a82bbbd92e46@ti.com> Date: Fri, 13 Jun 2025 15:30:57 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] drm/bridge: ti-sn65dsi86: Add HPD for DisplayPort connector type To: Tomi Valkeinen CC: , , , , , , , , , , , , , , , , , , , References: <20250611052947.5776-1-j-choudhary@ti.com> <9cd2f481-07e4-4c1e-9daa-aceeec47f871@ideasonboard.com> Content-Language: en-US From: Jayesh Choudhary In-Reply-To: <9cd2f481-07e4-4c1e-9daa-aceeec47f871@ideasonboard.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-C2ProcessedOrg: 333ef613-75bf-4e12-a4b1-8e3623f5dcea Hello Tomi, On 12/06/25 11:55, Tomi Valkeinen wrote: > Hi, > > On 11/06/2025 08:29, Jayesh Choudhary wrote: >> By default, HPD was disabled on SN65DSI86 bridge. When the driver was >> added (commit "a095f15c00e27"), the HPD_DISABLE bit was set in pre-enable >> call which was moved to other function calls subsequently. >> Later on, commit "c312b0df3b13" added detect utility for DP mode. But with >> HPD_DISABLE bit set, all the HPD events are disabled[0] and the debounced >> state always return 1 (always connected state). >> >> Set HPD_DISABLE bit conditionally based on connector type. >> Since the HPD_STATE is reflected correctly only after waiting for debounce >> time (~100-400ms) and adding this delay in detect() is not feasible >> owing to the performace impact (glitches and frame drop), remove runtime >> calls in detect() and add hpd_enable()/disable() bridge hooks with runtime >> calls, to detect hpd properly without any delay. >> >> [0]: (Pg. 32) >> >> Fixes: c312b0df3b13 ("drm/bridge: ti-sn65dsi86: Implement bridge connector operations for DP") >> Cc: Max Krummenacher >> Signed-off-by: Jayesh Choudhary >> --- >> >> Changelog v3->v4: >> - Remove "no-hpd" support due to backward compatibility issues >> - Change the conditional from "no-hpd" back to connector type >> but still address [1] >> >> v3 patch link: >> >> >> Changelog v2->v3: >> - Change conditional based on no-hpd property to address [1] >> - Remove runtime calls in detect() with appropriate comments >> - Add hpd_enable() and hpd_disable() in drm_bridge_funcs >> >> v2 patch link: >> >> >> Changelog v1->v2: >> - Drop additional property in bindings and use conditional. >> - Instead of register read for HPD state, use dpcd read which returns 0 >> for success and error codes for no connection >> - Add relevant history for the required change in commit message >> - Drop RFC subject-prefix in v2 >> - Add "Cc:" tag >> >> v1 patch link: >> >> >> [1]: >> >> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 49 ++++++++++++++++++++++----- >> 1 file changed, 41 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> index 60224f476e1d..b674a1aa1a37 100644 >> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c >> @@ -348,12 +348,20 @@ static void ti_sn65dsi86_enable_comms(struct ti_sn65dsi86 *pdata, >> * 200 ms. We'll assume that the panel driver will have the hardcoded >> * delay in its prepare and always disable HPD. >> * >> - * If HPD somehow makes sense on some future panel we'll have to >> - * change this to be conditional on someone specifying that HPD should >> - * be used. >> + * For DisplayPort connector type, now that HPD makes sense and is > > This comment also is written like a commit description ("now that HPD > makes sense"). I will make it more apt. > >> + * required, use the connector type to conditionally disable HPD. >> + * >> + * NOTE: The bridge type is set in auxiliary_bridge probe but >> + * enable_comms() can be called before. So for DisplayPort, >> + * HPD will be enabled once bridge type is set. >> + * "no-hpd" property is not used properly in devicetree description >> + * and hence is unreliable. Therefore HPD is being enabled using >> + * this conditional. >> */ >> - regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, HPD_DISABLE, >> - HPD_DISABLE); >> + >> + if (pdata->bridge.type != DRM_MODE_CONNECTOR_DisplayPort) >> + regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, HPD_DISABLE, >> + HPD_DISABLE); >> >> pdata->comms_enabled = true; >> >> @@ -1195,9 +1203,17 @@ static enum drm_connector_status ti_sn_bridge_detect(struct drm_bridge *bridge) >> struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge); >> int val = 0; >> >> - pm_runtime_get_sync(pdata->dev); >> + /* >> + * The chip won't report HPD right after being powered on as >> + * HPD_DEBOUNCED_STATE reflects correct state only after the >> + * debounce time (~100-400 ms). >> + * So having pm_runtime_get_sync() and immediately reading >> + * the register in detect() won't work, and adding delay() >> + * in detect will have performace impact in display. >> + * So remove runtime calls here. >> + */ >> + > > As Doug mentioned, the style here is more like a commit message. But > also, in my opinion, it would make more sense to have the comment in > hpd_enable() rather than having it here, mentioning that the chip needs > to be powered to have a reliable HPD due to the long debounce time. > So a comment here that runtime references are handled through hpd_enable() and hpd_disable() And then in enable(), mentioning that device needs to be powered on for reliable HPD in detect() due to debounce time >> regmap_read(pdata->regmap, SN_HPD_DISABLE_REG, &val); >> - pm_runtime_put_autosuspend(pdata->dev); >> >> return val & HPD_DEBOUNCED_STATE ? connector_status_connected >> : connector_status_disconnected; >> @@ -1220,6 +1236,20 @@ static void ti_sn65dsi86_debugfs_init(struct drm_bridge *bridge, struct dentry * >> debugfs_create_file("status", 0600, debugfs, pdata, &status_fops); >> } >> >> +static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge) >> +{ >> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge); >> + >> + pm_runtime_get_sync(pdata->dev); >> +} >> + >> +static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge) >> +{ >> + struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge); >> + >> + pm_runtime_put_sync(pdata->dev); > > No need for _sync, afaics. Why not pm_runtime_put_autosuspend()? Okay. > > Tomi > >> +} >> + >> static const struct drm_bridge_funcs ti_sn_bridge_funcs = { >> .attach = ti_sn_bridge_attach, >> .detach = ti_sn_bridge_detach, >> @@ -1234,6 +1264,8 @@ static const struct drm_bridge_funcs ti_sn_bridge_funcs = { >> .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state, >> .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state, >> .debugfs_init = ti_sn65dsi86_debugfs_init, >> + .hpd_enable = ti_sn_bridge_hpd_enable, >> + .hpd_disable = ti_sn_bridge_hpd_disable, >> }; >> >> static void ti_sn_bridge_parse_lanes(struct ti_sn65dsi86 *pdata, >> @@ -1322,7 +1354,8 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev, >> ? DRM_MODE_CONNECTOR_DisplayPort : DRM_MODE_CONNECTOR_eDP; >> >> if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) >> - pdata->bridge.ops = DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_DETECT; >> + pdata->bridge.ops = DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_DETECT | >> + DRM_BRIDGE_OP_HPD; >> >> drm_bridge_add(&pdata->bridge); >> > Thanks, Jayesh