From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0739DD75E32 for ; Fri, 22 Nov 2024 12:22:55 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C6D4D10EB5D; Fri, 22 Nov 2024 12:22:54 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="YHxOm46a"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) by gabe.freedesktop.org (Postfix) with ESMTPS id 44C1B10EB5D; Fri, 22 Nov 2024 12:22:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1732278173; x=1763814173; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=6N0+DV+e9pImJDMgKq8tG7PZiU4DXS+78Ssm1ANdnv4=; b=YHxOm46alyhHO+iw7UpZsLvzD6lIEl9oZ5Dt25nfZHmpFnD7LA9qRpqw 3tB2b+BVkQQeyIXTbhKxHZO8oNFUSz1JylIY8+liHZfMNyh0fOAub6oqX tAxxCxxrUmiOn0PJ5SPd/HAh6ZI0sFMkdplZRf2pLxkubh4tlPCF02f6s wIZ6pKTxJgFaOAMG3IQtRI+f15i21cq3WcpuIQgl5tSb8R5WyzT61N/zg BZbquxJoZ7pdlDSfZpGUizh/YoC3Joa2+6puKOpMJcMUvr3n00a+bieXi 3YlQiYvaZ0oW9iL4XHrQBh7k71O4rvFQtbP6X2p2/E81dbo1tlvr5Tt8R w==; X-CSE-ConnectionGUID: ptR2aI93QjCNNp786HuYdQ== X-CSE-MsgGUID: Om2SBtveQe69PavZ7VEnbQ== X-IronPort-AV: E=McAfee;i="6700,10204,11263"; a="32289751" X-IronPort-AV: E=Sophos;i="6.12,175,1728975600"; d="scan'208";a="32289751" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Nov 2024 04:22:53 -0800 X-CSE-ConnectionGUID: lYqwBKy7T9qqVT3HW1T1NA== X-CSE-MsgGUID: zeBFSAYwSuaPsr3k8gEaZg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,199,1725346800"; d="scan'208";a="95626860" Received: from jkrzyszt-mobl2.ger.corp.intel.com (HELO localhost) ([10.245.246.157]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Nov 2024 04:22:50 -0800 From: Jani Nikula To: imre.deak@intel.com Cc: Lyude Paul , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org Subject: Re: [PATCH 1/3] drm/dp: extract drm_dp_dpcd_poll_act_handled() In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <3d91f7b6639960fe688eb6ae0236254adae3e82d.1731942780.git.jani.nikula@intel.com> Date: Fri, 22 Nov 2024 14:22:44 +0200 Message-ID: <87bjy7zcdn.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Wed, 20 Nov 2024, Imre Deak wrote: > On Mon, Nov 18, 2024 at 05:14:52PM +0200, Jani Nikula wrote: >> SST with 128b/132b channel coding needs this too. Extract to a separate >> helper, independent of MST. >> >> Pass timeout in as a parameter, anticipating that we can reduce the >> timeout for SST. > > I wish there was a DP Standard section making the above clear, > but I suppose we just deduct that except of the side-band messaging, > every other payload programming and ACT signaling is required for > 128b/132b SST. Ping. Okay to merge, or do we want to mull over the the timeout? I'm primarily trying to do a non-functional change. I could omit the timeout parameter, but for non-hubs three seconds seems excessive, and reducing it for hubs too is a can of worms I prefer keeping the lid on top. > Cc: Lyude Paul > >> Signed-off-by: Jani Nikula >> --- >> drivers/gpu/drm/display/drm_dp_helper.c | 54 ++++++++++++++++++- >> drivers/gpu/drm/display/drm_dp_mst_topology.c | 36 +------------ >> include/drm/display/drm_dp_helper.h | 2 + >> 3 files changed, 57 insertions(+), 35 deletions(-) >> >> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c >> index 6ee51003de3c..b7e03bf02cd8 100644 >> --- a/drivers/gpu/drm/display/drm_dp_helper.c >> +++ b/drivers/gpu/drm/display/drm_dp_helper.c >> @@ -22,15 +22,16 @@ >> >> #include >> #include >> +#include >> #include >> #include >> #include >> +#include >> #include >> #include >> #include >> #include >> #include >> -#include >> >> #include >> #include >> @@ -779,6 +780,57 @@ int drm_dp_dpcd_read_phy_link_status(struct drm_dp_aux *aux, >> } >> EXPORT_SYMBOL(drm_dp_dpcd_read_phy_link_status); >> >> +static int read_payload_update_status(struct drm_dp_aux *aux) >> +{ >> + int ret; >> + u8 status; >> + >> + ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status); >> + if (ret < 0) >> + return ret; >> + >> + return status; >> +} >> + >> +/** >> + * drm_dp_dpcd_poll_act_handled() - Polls for ACT handled status. >> + * @aux: DisplayPort AUX channel >> + * @timeout_ms: Timeout in ms >> + * >> + * Tries waiting for the sink to finish updating its payload table by polling >> + * for the ACT handled bit for up to @timeout_ms milliseconds, defaulting to >> + * 3000 ms if 0. >> + * >> + * Returns: >> + * 0 if the ACT was handled in time, negative error code on failure. >> + */ >> +int drm_dp_dpcd_poll_act_handled(struct drm_dp_aux *aux, int timeout_ms) > > I wonder if it'd make sense to namespace these helpers using ll_mtp or mtp. Honestly I think there's already enough of an acronym jumble in the name. At least "drm_dp_dpcd" is common for most functions around here. BR, Jani. > >> +{ >> + int ret, status; >> + > > Extra w/s. > > Regardless of the namespace comment: > > Reviewed-by: Imre Deak > >> + /* default to 3 seconds, this is arbitrary */ >> + timeout_ms = timeout_ms ?: 3000; >> + >> + ret = readx_poll_timeout(read_payload_update_status, aux, status, >> + status & DP_PAYLOAD_ACT_HANDLED || status < 0, >> + 200, timeout_ms * USEC_PER_MSEC); >> + if (ret < 0 && status >= 0) { >> + drm_err(aux->drm_dev, "Failed to get ACT after %d ms, last status: %02x\n", >> + timeout_ms, status); >> + return -EINVAL; >> + } else if (status < 0) { >> + /* >> + * Failure here isn't unexpected - the hub may have >> + * just been unplugged >> + */ >> + drm_dbg_kms(aux->drm_dev, "Failed to read payload table status: %d\n", status); >> + return status; >> + } >> + >> + return 0; >> +} >> +EXPORT_SYMBOL(drm_dp_dpcd_poll_act_handled); >> + >> static bool is_edid_digital_input_dp(const struct drm_edid *drm_edid) >> { >> /* FIXME: get rid of drm_edid_raw() */ >> diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c >> index ac90118b9e7a..2bdbc1eb282b 100644 >> --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c >> +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c >> @@ -29,7 +29,6 @@ >> #include >> #include >> #include >> -#include >> >> #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) >> #include >> @@ -4723,18 +4722,6 @@ static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr, >> return ret; >> } >> >> -static int do_get_act_status(struct drm_dp_aux *aux) >> -{ >> - int ret; >> - u8 status; >> - >> - ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status); >> - if (ret < 0) >> - return ret; >> - >> - return status; >> -} >> - >> /** >> * drm_dp_check_act_status() - Polls for ACT handled status. >> * @mgr: manager to use >> @@ -4752,28 +4739,9 @@ int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr) >> * There doesn't seem to be any recommended retry count or timeout in >> * the MST specification. Since some hubs have been observed to take >> * over 1 second to update their payload allocations under certain >> - * conditions, we use a rather large timeout value. >> + * conditions, we use a rather large timeout value of 3 seconds. >> */ >> - const int timeout_ms = 3000; >> - int ret, status; >> - >> - ret = readx_poll_timeout(do_get_act_status, mgr->aux, status, >> - status & DP_PAYLOAD_ACT_HANDLED || status < 0, >> - 200, timeout_ms * USEC_PER_MSEC); >> - if (ret < 0 && status >= 0) { >> - drm_err(mgr->dev, "Failed to get ACT after %dms, last status: %02x\n", >> - timeout_ms, status); >> - return -EINVAL; >> - } else if (status < 0) { >> - /* >> - * Failure here isn't unexpected - the hub may have >> - * just been unplugged >> - */ >> - drm_dbg_kms(mgr->dev, "Failed to read payload table status: %d\n", status); >> - return status; >> - } >> - >> - return 0; >> + return drm_dp_dpcd_poll_act_handled(mgr->aux, 3000); >> } >> EXPORT_SYMBOL(drm_dp_check_act_status); >> >> diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h >> index 279624833ea9..38eea21d1082 100644 >> --- a/include/drm/display/drm_dp_helper.h >> +++ b/include/drm/display/drm_dp_helper.h >> @@ -567,6 +567,8 @@ int drm_dp_dpcd_read_phy_link_status(struct drm_dp_aux *aux, >> enum drm_dp_phy dp_phy, >> u8 link_status[DP_LINK_STATUS_SIZE]); >> >> +int drm_dp_dpcd_poll_act_handled(struct drm_dp_aux *aux, int timeout_ms); >> + >> bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux, >> u8 real_edid_checksum); >> >> -- >> 2.39.5 >> -- Jani Nikula, Intel