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 6F3E8C072A2 for ; Fri, 17 Nov 2023 11:01:12 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C117F10E745; Fri, 17 Nov 2023 11:01:05 +0000 (UTC) Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.126]) by gabe.freedesktop.org (Postfix) with ESMTPS id CB52C10E741; Fri, 17 Nov 2023 11:01:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1700218862; x=1731754862; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=BS2z8xr2yxPuq45YjtzipZHN/Ty84n1RpTfrIQHreD0=; b=aj7WPNacpAgBNg4/aeKxt3SmBYeozczS58H6yIB4mjHlnGIIrZWixmtq q00UETQ0KxeeCGOPox1fbKY/pkkA1D+CODUmX/r8kjxM6j0EC9IH4y7W7 2EdB9ms8kzGbcCK2z3u5CiypgTnUFBDG7fMoFRbhh5OJLpEDq0rl5F7Pn yjtVicGR4357BwVs3vsa14TL4SoIdVi9rNuZeeO8Whd8EmT6VMRwXekKk B7kjQxlxzrmMwg29QOjgfa0fte8BHjpZuUPNFdPaaPYt46IjGT7Mqn4ZL yDayBYfE3gUd1PnjNCObEe6MjmB0LNuIyBuBYhFu1BOE930urUfPNkq04 w==; X-IronPort-AV: E=McAfee;i="6600,9927,10896"; a="376327903" X-IronPort-AV: E=Sophos;i="6.04,206,1695711600"; d="scan'208";a="376327903" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Nov 2023 03:01:02 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10896"; a="759136059" X-IronPort-AV: E=Sophos;i="6.04,206,1695711600"; d="scan'208";a="759136059" Received: from stinkpipe.fi.intel.com (HELO stinkbox) ([10.237.72.74]) by orsmga007.jf.intel.com with SMTP; 17 Nov 2023 03:00:59 -0800 Received: by stinkbox (sSMTP sendmail emulation); Fri, 17 Nov 2023 13:00:58 +0200 Date: Fri, 17 Nov 2023 13:00:58 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Imre Deak Message-ID: References: <20231116131841.1588781-1-imre.deak@intel.com> <20231116131841.1588781-3-imre.deak@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20231116131841.1588781-3-imre.deak@intel.com> X-Patchwork-Hint: comment Subject: Re: [Intel-gfx] [PATCH v2 02/11] drm/dp_mst: Fix PBN divider calculation for UHBR rates X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Thu, Nov 16, 2023 at 03:18:32PM +0200, Imre Deak wrote: > The current way of calculating the pbn_div value, the link BW per each > MTP slot, worked only for DP 1.4 link rates. Fix things up for UHBR > rates calculating with the correct channel coding efficiency based on > the link rate. > > v2: > - Return the fractional pbn_div value from drm_dp_get_vc_payload_bw(). > > Cc: Lyude Paul > Cc: dri-devel@lists.freedesktop.org > Signed-off-by: Imre Deak > --- > drivers/gpu/drm/display/drm_dp_mst_topology.c | 13 ++++++++++--- > include/drm/display/drm_dp_helper.h | 13 +++++++++++++ > 2 files changed, 23 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c > index 000d05e80352a..3fbd5585d5e6c 100644 > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > @@ -3585,14 +3585,18 @@ static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr, > fixed20_12 drm_dp_get_vc_payload_bw(const struct drm_dp_mst_topology_mgr *mgr, > int link_rate, int link_lane_count) > { > + int ch_coding_efficiency = > + drm_dp_bw_channel_coding_efficiency(drm_dp_is_uhbr_rate(link_rate)); > fixed20_12 ret; > > if (link_rate == 0 || link_lane_count == 0) > drm_dbg_kms(mgr->dev, "invalid link rate/lane count: (%d / %d)\n", > link_rate, link_lane_count); > > - /* See DP v2.0 2.6.4.2, VCPayload_Bandwidth_for_OneTimeSlotPer_MTP_Allocation */ > - ret.full = dfixed_const(link_rate * link_lane_count / 54000); > + /* See DP v2.0 2.6.4.2, 2.7.6.3 VCPayload_Bandwidth_for_OneTimeSlotPer_MTP_Allocation */ > + ret.full = DIV_ROUND_DOWN_ULL(mul_u32_u32(link_rate * link_lane_count, > + ch_coding_efficiency), > + (1000000ULL * 8 * 5400) >> 12); Seems to produce the correct numbers. > > return ret; > } > @@ -4315,6 +4319,7 @@ int drm_dp_atomic_find_time_slots(struct drm_atomic_state *state, > struct drm_dp_mst_atomic_payload *payload = NULL; > struct drm_connector_state *conn_state; > int prev_slots = 0, prev_bw = 0, req_slots; > + fixed20_12 req_slots_fp; > > topology_state = drm_atomic_get_mst_topology_state(state, mgr); > if (IS_ERR(topology_state)) > @@ -4342,7 +4347,9 @@ int drm_dp_atomic_find_time_slots(struct drm_atomic_state *state, > } > } > > - req_slots = DIV_ROUND_UP(pbn, dfixed_trunc(topology_state->pbn_div)); > + req_slots_fp.full = dfixed_div((fixed20_12)dfixed_init(pbn), topology_state->pbn_div); dfixed_div() looks super dodgy. It seems to have some kind of hand rolled round to closest behaviour, which would imply that this can return a rounded down result. > + req_slots_fp.full = dfixed_ceil(req_slots_fp); > + req_slots = dfixed_trunc(req_slots_fp); > > drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] TU %d -> %d\n", > port->connector->base.id, port->connector->name, > diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h > index c5f1079acb3b1..863b2e7add29e 100644 > --- a/include/drm/display/drm_dp_helper.h > +++ b/include/drm/display/drm_dp_helper.h > @@ -252,6 +252,19 @@ drm_edp_backlight_supported(const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE]) > return !!(edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP); > } > > +/** > + * drm_dp_is_uhbr_rate - Determine if a link rate is UHBR > + * @link_rate: link rate in 10kbits/s units > + * > + * Determine if the provided link rate is an UHBR rate. > + * > + * Returns: %True if @link_rate is an UHBR rate. > + */ > +static inline bool drm_dp_is_uhbr_rate(int link_rate) > +{ > + return link_rate >= 1000000; > +} > + > /* > * DisplayPort AUX channel > */ > -- > 2.39.2 -- Ville Syrjälä Intel