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 5E356C27C53 for ; Wed, 19 Jun 2024 14:44:13 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E94D710ECE2; Wed, 19 Jun 2024 14:44:12 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="LOv8feHt"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.14]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8064D10ECE2 for ; Wed, 19 Jun 2024 14:44:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1718808252; x=1750344252; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=aMKiR/7alCNCK7SfGkEb5DDJj8CvOr5E8G8YH/3RvQ0=; b=LOv8feHtDa6KYo3Ts+xLuL8I3TyU6+owiXp0tbztlTDSmp1OAuKT1KC5 wNOabLVqdoaFg/d/tKHXSZUMsQTf+jGCv6MQVAWIyVF1FaMuIziH8LDvr cOnK+vRDYjXzG92hP7EV2ardPfuJTMq+ThOL419rJS/Gh5aH7gXK8GkpH NUpXowyRti8dGxHd4b6oK3ZuGnevSDj3p/C7r8cy9IgoTptItvwArhQsw xO/lHjwFAzBY3i4S2a9LHeoueYQEl9V26iI+Qj4f1fXSXBjFS8GD79uck SDPhaHQzsCbC+MH+y1A7CqckgwEHChSlyq9vDa2bOxQrw/JRJkvq2hgTH w==; X-CSE-ConnectionGUID: 5MW+6wH6SHSCe0rMHtPh/w== X-CSE-MsgGUID: 2uNTsOBkSL2AfDsla5nGFw== X-IronPort-AV: E=McAfee;i="6700,10204,11108"; a="15983886" X-IronPort-AV: E=Sophos;i="6.08,250,1712646000"; d="scan'208";a="15983886" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jun 2024 07:44:11 -0700 X-CSE-ConnectionGUID: sPybO1YPT0+naOI51YKphQ== X-CSE-MsgGUID: vasC3T4yS6Kc5I1MJ1FBCQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,250,1712646000"; d="scan'208";a="41893563" Received: from stinkpipe.fi.intel.com (HELO stinkbox) ([10.237.72.74]) by fmviesa008.fm.intel.com with SMTP; 19 Jun 2024 07:44:09 -0700 Received: by stinkbox (sSMTP sendmail emulation); Wed, 19 Jun 2024 17:44:08 +0300 Date: Wed, 19 Jun 2024 17:44:08 +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 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. -- Ville Syrjälä Intel