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 7983CC48295 for ; Mon, 5 Feb 2024 15:35:02 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E315A10EE20; Mon, 5 Feb 2024 15:35:01 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="H0/fG0LO"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.17]) by gabe.freedesktop.org (Postfix) with ESMTPS id 31B6E10EE20 for ; Mon, 5 Feb 2024 15:35:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1707147301; x=1738683301; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=HI9785amhLMK1G264623OpgCdAM4ctSTD5saAgE6wug=; b=H0/fG0LOgPxE55kXIO82Y10zU59PBA9fzCDe6Czn8DDlUOvHBbBoHXSt YW8RAUPXwPTUDNOctFLPb0oAou67RkqRTK5TdGYSXoBdhY/L71XkJF/8t eJqhWIAMudvv3lmxY0aXHpd0t+ok05ct6GJk0efjrpTp+0VsGOKdp8CGy y2LDVciXXOa/iiUQ53REbMQG/9y1rgbYkZfxY21uLqKr4Ephbp0lGS6lK oe7wZuDHHVx/uqolDK0IY+ec2ELpNFwxuP2YDGfRGWS1bEh9PChonX6d1 lebMDFTkTgWozeAaaIL04ebJVCi/38Wk3CCNxNf+IYI4O99vK9BmXrGhC g==; X-IronPort-AV: E=McAfee;i="6600,9927,10975"; a="692379" X-IronPort-AV: E=Sophos;i="6.05,245,1701158400"; d="scan'208";a="692379" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Feb 2024 07:35:01 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10975"; a="823886226" X-IronPort-AV: E=Sophos;i="6.05,245,1701158400"; d="scan'208";a="823886226" Received: from stinkpipe.fi.intel.com (HELO stinkbox) ([10.237.72.74]) by orsmga001.jf.intel.com with SMTP; 05 Feb 2024 07:34:58 -0800 Received: by stinkbox (sSMTP sendmail emulation); Mon, 05 Feb 2024 17:34:57 +0200 Date: Mon, 5 Feb 2024 17:34:57 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Gustavo Sousa Cc: intel-gfx@lists.freedesktop.org Subject: Re: [PATCH] drm/i915/cdclk: Rename intel_cdclk_needs_modeset to intel_cdclk_params_changed Message-ID: References: <20240202131208.453298-1-gustavo.sousa@intel.com> <170696671884.1816.11371833747153807417@gjsousa-mobl2> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <170696671884.1816.11371833747153807417@gjsousa-mobl2> X-Patchwork-Hint: comment 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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Sat, Feb 03, 2024 at 10:25:18AM -0300, Gustavo Sousa wrote: > Quoting Ville Syrjälä (2024-02-02 16:58:37-03:00) > >On Fri, Feb 02, 2024 at 10:12:08AM -0300, Gustavo Sousa wrote: > >> Looks like the name and description of intel_cdclk_needs_modeset() > >> became inacurate as of commit 59f9e9cab3a1 ("drm/i915: Skip modeset for > >> cdclk changes if possible"), when it became possible to update the cdclk > >> without requiring disabling the pipes when only changing the cd2x > >> divider was enough. > >> > >> Later on we also added the same type of support with squash and crawling > >> with commit 25e0e5ae5610 ("drm/i915/display: Do both crawl and squash > >> when changing cdclk"), commit d4a23930490d ("drm/i915: Allow cdclk > >> squasher to be reconfigured live") and commit d62686ba3b54 > >> ("drm/i915/adl_p: CDCLK crawl support for ADL"). > >> > >> As such, update that function's name and documentation to something more > >> appropriate, since the real checks for requiring modeset are done > >> elsewhere. > >> > >> Signed-off-by: Gustavo Sousa > >> --- > >> > >> One thing worth noting here is that, with this change, we are left with an > >> awkward situation where two function names related to checking changes in cdclk: > >> > >> intel_cdclk_params_changed() and intel_cdclk_changed() > >> > >> , > >> > >> and I find it weird that we have intel_cdclk_changed(), which checks for the > >> voltage level as well. Shouldn't the voltage level be a function of cdclk and > >> ddi clock? Why do we need that? > >> > >> drivers/gpu/drm/i915/display/intel_cdclk.c | 15 +++++++-------- > >> drivers/gpu/drm/i915/display/intel_cdclk.h | 4 ++-- > >> .../drm/i915/display/intel_display_power_well.c | 4 ++-- > >> 3 files changed, 11 insertions(+), 12 deletions(-) > >> > >> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c > >> index 26200ee3e23f..caadd880865f 100644 > >> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c > >> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c > >> @@ -2233,17 +2233,16 @@ static bool intel_cdclk_can_squash(struct drm_i915_private *dev_priv, > >> } > >> > >> /** > >> - * intel_cdclk_needs_modeset - Determine if changong between the CDCLK > >> - * configurations requires a modeset on all pipes > >> + * intel_cdclk_params_changed - Check whether CDCLK parameters changed > >> * @a: first CDCLK configuration > >> * @b: second CDCLK configuration > >> * > >> * Returns: > >> - * True if changing between the two CDCLK configurations > >> - * requires all pipes to be off, false if not. > >> + * True if parameters changed in a way that requires programming the CDCLK > >> + * and False otherwise. > >> */ > >> -bool intel_cdclk_needs_modeset(const struct intel_cdclk_config *a, > >> - const struct intel_cdclk_config *b) > >> +bool intel_cdclk_params_changed(const struct intel_cdclk_config *a, > >> + const struct intel_cdclk_config *b) > > > >The new name isn't very descriptive either. > > Yeah... I would much rather use intel_cdclk_changed(), but that one is > already taken. > > > > >Outside the cd2x/crawl/squash cases we stil have to consider > >two cases: > >1. cdclk frequency/pll changes (voltage level can change or not) > >2. cdclk frequency/pll doesn't change, but voltage level needs to change > > > >And that difference is what intel_cdclk_needs_modeset() is trying > >convey. And intel_cdclk_changed() tells us whether anything at all > >is changing. > > I might be missing something, but, by going through the specs, it looked > to me that voltage level was dependent on cdclk (as well as on ddi > clock) and not the other way around. That's why I find it odd that we > need an intel_cdclk_changed() that, besides looking for changes in > cdclk, also checks for the voltage level. > > In intel_set_cdclk(), we check intel_cdclk_changed() before continuing. > If, for example, there is a change in ddi clock that requires a change > in voltage level but no changes in cdclk, intel_cdclk_changed() would > return true, right? Wouldn't that make us unnecessarily go through > intel_set_cdclk()? intel_set_cdclk() is the thing that does the voltage change. -- Ville Syrjälä Intel