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 X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6876C433DF for ; Sat, 27 Jun 2020 16:57:37 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 8F379206C0 for ; Sat, 27 Jun 2020 16:57:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F379206C0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1D8186E0FC; Sat, 27 Jun 2020 16:57:36 +0000 (UTC) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id D049E6E0FC for ; Sat, 27 Jun 2020 16:57:34 +0000 (UTC) IronPort-SDR: efpEsnvVRU0Y8+xr5K17zOx+gV3cvPJ5p0k4z2cLqptDenSO+OP1VNF58JRuPWmWKdvNw+oX0p ALrzzBgqjqDg== X-IronPort-AV: E=McAfee;i="6000,8403,9665"; a="144758785" X-IronPort-AV: E=Sophos;i="5.75,287,1589266800"; d="scan'208";a="144758785" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2020 09:57:34 -0700 IronPort-SDR: 7ZAcC2b+sC2kD/+H9v6PHRyTuvDvyKA9dfBVw1vJhRuGolHH9vsbr325ZKu+tYdMBuzUozUasi C+qMMgH/+emg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,287,1589266800"; d="scan'208";a="320267104" Received: from stinkbox.fi.intel.com (HELO stinkbox) ([10.237.72.174]) by FMSMGA003.fm.intel.com with SMTP; 27 Jun 2020 09:57:32 -0700 Received: by stinkbox (sSMTP sendmail emulation); Sat, 27 Jun 2020 19:57:31 +0300 Date: Sat, 27 Jun 2020 19:57:31 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: "Lisovskiy, Stanislav" Message-ID: <20200626180306.GC6112@intel.com> References: <20200625200003.12436-1-ville.syrjala@linux.intel.com> <20200626091606.GA29269@intel.com> <20200626134641.GZ6112@intel.com> <20200626151336.GA6490@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200626151336.GA6490@intel.com> X-Patchwork-Hint: comment User-Agent: Mutt/1.10.1 (2018-07-13) Subject: Re: [Intel-gfx] [PATCH] drm/i915: Clamp linetime wm to <64usec 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 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Fri, Jun 26, 2020 at 06:13:36PM +0300, Lisovskiy, Stanislav wrote: > On Fri, Jun 26, 2020 at 04:46:41PM +0300, Ville Syrj=E4l=E4 wrote: > > On Fri, Jun 26, 2020 at 12:16:06PM +0300, Lisovskiy, Stanislav wrote: > > > On Thu, Jun 25, 2020 at 11:00:03PM +0300, Ville Syrjala wrote: > > > > From: Ville Syrj=E4l=E4 > > > > = > > > > The linetime watermark is a 9 bit value, which gives us > > > > a maximum linetime of just below 64 usec. If the linetime > > > > exceeds that value we currently just discard the high bits > > > > and program the rest into the register, which angers the > > > > state checker. > > > > = > > > > To avoid that let's just clamp the value to the max. I believe > > > > it should be perfectly fine to program a smaller linetime wm > > > > than strictly required, just means the hardware may fetch data > > > > sooner than strictly needed. We are further reassured by the > > > > fact that with DRRS the spec tells us to program the smaller > > > > of the two linetimes corresponding to the two refresh rates. > > > > = > > > > Cc: Stanislav Lisovskiy > > > > Signed-off-by: Ville Syrj=E4l=E4 > > > > --- > > > > drivers/gpu/drm/i915/display/intel_display.c | 18 ++++++++++++----= -- > > > > 1 file changed, 12 insertions(+), 6 deletions(-) > > > > = > > > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers= /gpu/drm/i915/display/intel_display.c > > > > index a11bb675f9b3..d486d675166f 100644 > > > > --- a/drivers/gpu/drm/i915/display/intel_display.c > > > > +++ b/drivers/gpu/drm/i915/display/intel_display.c > > > > @@ -12581,12 +12581,15 @@ static u16 hsw_linetime_wm(const struct i= ntel_crtc_state *crtc_state) > > > > { > > > > const struct drm_display_mode *adjusted_mode =3D > > > > &crtc_state->hw.adjusted_mode; > > > > + int linetime_wm; > > > > = > > > > if (!crtc_state->hw.enable) > > > > return 0; > > > > = > > > > - return DIV_ROUND_CLOSEST(adjusted_mode->crtc_htotal * 1000 * 8, > > > > - adjusted_mode->crtc_clock); > > > > + linetime_wm =3D DIV_ROUND_CLOSEST(adjusted_mode->crtc_htotal * 10= 00 * 8, > > > > + adjusted_mode->crtc_clock); > > > > + > > > > + return min(linetime_wm, 0x1ff); > > > = > > > Are we actually doing the right thing here? I just mean that we get v= alue > > > 543 in the bug because pixel rate is 14874 which doesn't seem correct. > > = > > As explained in the commit msg programming this to lower than necessary > > value should be totally fine. It just won't be optimal. > > = > > The values in the jira (was there an actual gitlab bug for this btw?) > > look quite sensible to me. Some kind of low res 848xsomething mode with > > dotclock of 14.874 Mhz, which gives us that linetime of ~68 usec. > = > Htotal from modeline "848x480": 30 14874 848 896 928 1008 480 483 488 494= 0x40 0x9 > is 1008. > = > According to the formula above htotal(1008)*1000*8 / 14874(crtc_clock) = =3D 542.154 > = > So what's the catch? :) What catch? Looks totally consistent to me. > = > Stan > > = > > > = > > > Stan > > > > } > > > > = > > > > static u16 hsw_ips_linetime_wm(const struct intel_crtc_state *crtc= _state, > > > > @@ -12594,12 +12597,15 @@ static u16 hsw_ips_linetime_wm(const stru= ct intel_crtc_state *crtc_state, > > > > { > > > > const struct drm_display_mode *adjusted_mode =3D > > > > &crtc_state->hw.adjusted_mode; > > > > + int linetime_wm; > > > > = > > > > if (!crtc_state->hw.enable) > > > > return 0; > > > > = > > > > - return DIV_ROUND_CLOSEST(adjusted_mode->crtc_htotal * 1000 * 8, > > > > - cdclk_state->logical.cdclk); > > > > + linetime_wm =3D DIV_ROUND_CLOSEST(adjusted_mode->crtc_htotal * 10= 00 * 8, > > > > + cdclk_state->logical.cdclk); > > > > + > > > > + return min(linetime_wm, 0x1ff); > > > > } > > > > = > > > > static u16 skl_linetime_wm(const struct intel_crtc_state *crtc_sta= te) > > > > @@ -12608,7 +12614,7 @@ static u16 skl_linetime_wm(const struct int= el_crtc_state *crtc_state) > > > > struct drm_i915_private *dev_priv =3D to_i915(crtc->base.dev); > > > > const struct drm_display_mode *adjusted_mode =3D > > > > &crtc_state->hw.adjusted_mode; > > > > - u16 linetime_wm; > > > > + int linetime_wm; > > > > = > > > > if (!crtc_state->hw.enable) > > > > return 0; > > > > @@ -12620,7 +12626,7 @@ static u16 skl_linetime_wm(const struct int= el_crtc_state *crtc_state) > > > > if (IS_GEN9_LP(dev_priv) && dev_priv->ipc_enabled) > > > > linetime_wm /=3D 2; > > > > = > > > > - return linetime_wm; > > > > + return min(linetime_wm, 0x1ff); > > > > } > > > > = > > > > static int hsw_compute_linetime_wm(struct intel_atomic_state *stat= e, > > > > -- = > > > > 2.26.2 > > > > = > > = > > -- = > > Ville Syrj=E4l=E4 > > Intel -- = Ville Syrj=E4l=E4 Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx