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 C0F0FC27C53 for ; Wed, 19 Jun 2024 14:55:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4635810ECF8; Wed, 19 Jun 2024 14:55:17 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="Fap506Xp"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.17]) by gabe.freedesktop.org (Postfix) with ESMTPS id 51AB310ECEA for ; Wed, 19 Jun 2024 14:55:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1718808916; x=1750344916; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=rNapJcwXS4xgvbo7HuOHC9LQ9jO4FCrDj8zhCBjCPDQ=; b=Fap506Xp4BuvKVsyPDr3kYc+/DHR+Z9IfLBp5MUNQupheFz0ILYeJpMc rTgW++m+sAJFDu53+/diqaxlPagzcKh6lsNfAn6dR50IgeI1rMid8i10D 94oD/hgBFX/d4l931WFwhO0EuR/oIi7QvoUwaaZb0ygAuGSBe2G1NXU8j sldVbbsiPDcsGFnMHz+6TOOM7DlrEosriivrrgijz/loBSeqVLmFQ/6mT lCbEnSPO/snN+sNd2n3hDmfvrV+IOK3cdWgx//hSydT3haUAGrXGiLyA1 28jHueOsbm/NHjoK3VRSIIc8CJ2ikMrCOe7KPNbtvKUo+fbUUqbPC8yHa A==; X-CSE-ConnectionGUID: 6VyXCggrRjmPo75m2bnuNA== X-CSE-MsgGUID: cdKX34JJSCGmbVzdV0+wxg== X-IronPort-AV: E=McAfee;i="6700,10204,11108"; a="15869348" X-IronPort-AV: E=Sophos;i="6.08,250,1712646000"; d="scan'208";a="15869348" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jun 2024 07:55:15 -0700 X-CSE-ConnectionGUID: SGFniZTfRhWQqB3iP2ccMA== X-CSE-MsgGUID: kJNd8cJQRd600AlOK81PeQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,250,1712646000"; d="scan'208";a="41895543" Received: from stinkpipe.fi.intel.com (HELO stinkbox) ([10.237.72.74]) by fmviesa008.fm.intel.com with SMTP; 19 Jun 2024 07:55:13 -0700 Received: by stinkbox (sSMTP sendmail emulation); Wed, 19 Jun 2024 17:55:11 +0300 Date: Wed, 19 Jun 2024 17:55:11 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Jani Nikula Cc: intel-gfx@lists.freedesktop.org Subject: Re: [PATCH 08/11] drm/i915/dsb: Add i915.enable_dsb module parameter Message-ID: References: <20240611133344.30673-1-ville.syrjala@linux.intel.com> <20240611133344.30673-9-ville.syrjala@linux.intel.com> <875xu6h5kj.fsf@intel.com> <8734p9f577.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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 Wed, Jun 19, 2024 at 05:44:08PM +0300, Ville Syrjälä wrote: > On Wed, Jun 19, 2024 at 04:24:16PM +0300, Ville Syrjälä wrote: > > On Wed, Jun 19, 2024 at 04:11:08PM +0300, Jani Nikula wrote: > > > On Wed, 19 Jun 2024, Ville Syrjälä wrote: > > > > On Tue, Jun 18, 2024 at 02:07:56PM +0300, Jani Nikula wrote: > > > >> On Tue, 11 Jun 2024, Ville Syrjala wrote: > > > >> > From: Ville Syrjälä > > > >> > > > > >> > As we extend the use of DSB for critical pipe/plane register > > > >> > programming, it'll be nice to have an escape valve at hand, > > > >> > in case things go very poorly. To that end, add a i915.enable_dsb > > > >> > modparam by which we can force the driver to take the pure mmio > > > >> > path instead. > > > >> > > > > >> > Signed-off-by: Ville Syrjälä > > > >> > --- > > > >> > drivers/gpu/drm/i915/display/intel_display_params.c | 3 +++ > > > >> > drivers/gpu/drm/i915/display/intel_display_params.h | 1 + > > > >> > drivers/gpu/drm/i915/display/intel_dsb.c | 3 +++ > > > >> > 3 files changed, 7 insertions(+) > > > >> > > > > >> > diff --git a/drivers/gpu/drm/i915/display/intel_display_params.c b/drivers/gpu/drm/i915/display/intel_display_params.c > > > >> > index aebdb7b59dbf..449a31767791 100644 > > > >> > --- a/drivers/gpu/drm/i915/display/intel_display_params.c > > > >> > +++ b/drivers/gpu/drm/i915/display/intel_display_params.c > > > >> > @@ -54,6 +54,9 @@ intel_display_param_named_unsafe(enable_dc, int, 0400, > > > >> > intel_display_param_named_unsafe(enable_dpt, bool, 0400, > > > >> > "Enable display page table (DPT) (default: true)"); > > > >> > > > > >> > +intel_display_param_named_unsafe(enable_dsb, bool, 0600, > > > >> > + "Enable display state buffer (DSB) (default: true)"); > > > >> > > > >> Not much point in leaving the module param 0600, is there? > > > > > > > > It'll let you try both dsb and mmio paths at runtime without > > > > having to do a full reboot/reload. > > > > > > I mean does any code actually look at the *module* parameter runtime? > > > It's only the initial value for the device param? > > > > You can change it via the debugfs i915_params/* thing. > > Apparently the modparam vs. debugfs permissions are specified in two > different places. This is rather confusing. > > Is there no way to put them in the same place? Or can we just nuke > the permission stuff from the modparam macro entirely so it won't > end up confusing me again? Looks like there is exactly one (gem related) > modparam that uses 0600, everything else seems to be 0400. And even that seems to use the per-device copy in the actual code. So looks to me like we can just rip out the macro argument and make it 0400 always. -- Ville Syrjälä Intel