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 C38EEC433EF for ; Tue, 3 May 2022 17:29:34 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5E98C10E34E; Tue, 3 May 2022 17:29:34 +0000 (UTC) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id BA97010E34E for ; Tue, 3 May 2022 17:29:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651598972; x=1683134972; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=srPjVSuOAsgpnxqyvWr+bgJ4JeLXUFf6kkCgn/3HqWU=; b=M1KqKDjPnOLBZgtRi1t9eZAfp8NYxcVhtuWmRCsRgLoFb8CUfzf/ng3D FKiFf13Yq/e2kX3Cqanl9+pvNT2NPBw0Hf5KHZZmCTVwxaxHNAkW7KPC9 GEz7J09zjP6nnz3nWMqgOHDf4R4Q+mImwlgDz+Qa3lBwmDRPY8VsqTF2q t8FOP2GhcduRkBNRzlH5WrSM96Vsft5TO8csCYr/AFZ+Klg7k+QyYuqoe MF3TdHvlr3i0N/q/SnLrpechMN1VsFRc7bJcWFRp9lLa3vIc8Ld2SVzZN pWmNVCEmYyKpvbWmkKrn2N0C2ehx8HUN3UUQqUNxnCMmpUNqYbnAu0Q9g w==; X-IronPort-AV: E=McAfee;i="6400,9594,10336"; a="330524957" X-IronPort-AV: E=Sophos;i="5.91,195,1647327600"; d="scan'208";a="330524957" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 May 2022 10:29:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,195,1647327600"; d="scan'208";a="562306003" Received: from stinkpipe.fi.intel.com (HELO stinkbox) ([10.237.72.51]) by orsmga007.jf.intel.com with SMTP; 03 May 2022 10:29:15 -0700 Received: by stinkbox (sSMTP sendmail emulation); Tue, 03 May 2022 20:29:14 +0300 Date: Tue, 3 May 2022 20:29:14 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Jani Nikula Message-ID: References: <20220426193222.3422-1-ville.syrjala@linux.intel.com> <20220426193222.3422-3-ville.syrjala@linux.intel.com> <87o80eriln.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: <87o80eriln.fsf@intel.com> X-Patchwork-Hint: comment Subject: Re: [Intel-gfx] [PATCH v3 02/18] drm/i915/bios: Generate LFP data table pointers if the VBT lacks them 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 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Tue, May 03, 2022 at 01:55:16PM +0300, Jani Nikula wrote: > On Tue, 26 Apr 2022, Ville Syrjala wrote: > > From: Ville Syrjälä > > > > Modern VBTs no longer contain the LFP data table pointers > > block (41). We are expecting to have one in order to be able > > to parse the LFP data block (42), so let's make one up. > > > > Since the fp_timing table has variable size we must somehow > > determine its size. Rather than just hardcode it we look for > > the terminator bytes (0xffff) to figure out where each table > > entry starts. dvo_timing, panel_pnp_id, and panel_name are > > expected to have fixed size. > > > > This has been observed on various machines, eg. TGL with BDB > > version 240, CML with BDB version 231, etc. The most recent > > VBT I've observed that still had block 41 had BDB version > > 228. So presumably the cutoff (if an exact cutoff even exists) > > is somewhere around BDB version 229-231. > > > > v2: kfree the thing we allocated, not the thing+3 bytes > > v3: Do the debugprint only if we found the LFP data block > > v4: Fix t0 null check (Jani) > > > > Signed-off-by: Ville Syrjälä > > I've reviewed this as best as I could. It's awful, but I couldn't really > come up with concrete suggestions either. Maybe there could be temp > variables with more helpful naming. Maybe there could be some more > explanatory comments. I don't know. But I couldn't spot any obvious > mistakes. The alternative I think that could work is just hardcoding it based on the assumption that it'll stay a fixed size from here on out. But then I think we would want also to make validate_lfp_data_ptrs() check that the terminators appear at the expected spots, just in case it does end up changing size at some point. That approach might be a bit easier on the brain I guess. > > Reviewed-by: Jani Nikula > > > --- > > drivers/gpu/drm/i915/display/intel_bios.c | 134 +++++++++++++++++++++- > > 1 file changed, 133 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c > > index 8a1086721525..7bc3d55b6bb0 100644 > > --- a/drivers/gpu/drm/i915/display/intel_bios.c > > +++ b/drivers/gpu/drm/i915/display/intel_bios.c > > @@ -311,16 +311,144 @@ static bool fixup_lfp_data_ptrs(const void *bdb, void *ptrs_block) > > return validate_lfp_data_ptrs(bdb, ptrs); > > } > > > > +static const void *find_fp_timing_terminator(const u8 *data, int size) > > +{ > > + int i; > > + > > + for (i = 0; i < size - 1; i++) { > > + if (data[i] == 0xff && data[i+1] == 0xff) > > + return &data[i]; > > + } > > + > > + return NULL; > > +} > > + > > +static int make_lfp_data_ptr(struct lvds_lfp_data_ptr_table *table, > > + int table_size, int total_size) > > +{ > > + if (total_size < table_size) > > + return total_size; > > + > > + table->table_size = table_size; > > + table->offset = total_size - table_size; > > + > > + return total_size - table_size; > > +} > > + > > +static void next_lfp_data_ptr(struct lvds_lfp_data_ptr_table *next, > > + const struct lvds_lfp_data_ptr_table *prev, > > + int size) > > +{ > > + next->table_size = prev->table_size; > > + next->offset = prev->offset + size; > > +} > > + > > +static void *generate_lfp_data_ptrs(struct drm_i915_private *i915, > > + const void *bdb) > > +{ > > + int i, size, table_size, block_size, offset; > > + const void *t0, *t1, *block; > > + struct bdb_lvds_lfp_data_ptrs *ptrs; > > + void *ptrs_block; > > + > > + block = find_raw_section(bdb, BDB_LVDS_LFP_DATA); > > + if (!block) > > + return NULL; > > + > > + drm_dbg_kms(&i915->drm, "Generating LFP data table pointers\n"); > > + > > + block_size = get_blocksize(block); > > + > > + size = block_size; > > + t0 = find_fp_timing_terminator(block, size); > > + if (!t0) > > + return NULL; > > + > > + size -= t0 - block - 2; > > + t1 = find_fp_timing_terminator(t0 + 2, size); > > + if (!t1) > > + return NULL; > > + > > + size = t1 - t0; > > + if (size * 16 > block_size) > > + return NULL; > > + > > + ptrs_block = kzalloc(sizeof(*ptrs) + 3, GFP_KERNEL); > > + if (!ptrs_block) > > + return NULL; > > + > > + *(u8 *)(ptrs_block + 0) = BDB_LVDS_LFP_DATA_PTRS; > > + *(u16 *)(ptrs_block + 1) = sizeof(*ptrs); > > + ptrs = ptrs_block + 3; > > + > > + table_size = sizeof(struct lvds_pnp_id); > > + size = make_lfp_data_ptr(&ptrs->ptr[0].panel_pnp_id, table_size, size); > > + > > + table_size = sizeof(struct lvds_dvo_timing); > > + size = make_lfp_data_ptr(&ptrs->ptr[0].dvo_timing, table_size, size); > > + > > + table_size = t0 - block + 2; > > + size = make_lfp_data_ptr(&ptrs->ptr[0].fp_timing, table_size, size); > > + > > + if (ptrs->ptr[0].fp_timing.table_size) > > + ptrs->lvds_entries++; > > + if (ptrs->ptr[0].dvo_timing.table_size) > > + ptrs->lvds_entries++; > > + if (ptrs->ptr[0].panel_pnp_id.table_size) > > + ptrs->lvds_entries++; > > + > > + if (size != 0 || ptrs->lvds_entries != 3) { > > + kfree(ptrs); > > + return NULL; > > + } > > + > > + size = t1 - t0; > > + for (i = 1; i < 16; i++) { > > + next_lfp_data_ptr(&ptrs->ptr[i].fp_timing, &ptrs->ptr[i-1].fp_timing, size); > > + next_lfp_data_ptr(&ptrs->ptr[i].dvo_timing, &ptrs->ptr[i-1].dvo_timing, size); > > + next_lfp_data_ptr(&ptrs->ptr[i].panel_pnp_id, &ptrs->ptr[i-1].panel_pnp_id, size); > > + } > > + > > + size = t1 - t0; > > + table_size = sizeof(struct lvds_lfp_panel_name); > > + > > + if (16 * (size + table_size) <= block_size) { > > + ptrs->panel_name.table_size = table_size; > > + ptrs->panel_name.offset = size * 16; > > + } > > + > > + offset = block - bdb; > > + > > + for (i = 0; i < 16; i++) { > > + ptrs->ptr[i].fp_timing.offset += offset; > > + ptrs->ptr[i].dvo_timing.offset += offset; > > + ptrs->ptr[i].panel_pnp_id.offset += offset; > > + } > > + > > + if (ptrs->panel_name.table_size) > > + ptrs->panel_name.offset += offset; > > + > > + return ptrs_block; > > +} > > + > > static void > > init_bdb_block(struct drm_i915_private *i915, > > const void *bdb, enum bdb_block_id section_id, > > size_t min_size) > > { > > struct bdb_block_entry *entry; > > + void *temp_block = NULL; > > const void *block; > > size_t block_size; > > > > block = find_raw_section(bdb, section_id); > > + > > + /* Modern VBTs lack the LFP data table pointers block, make one up */ > > + if (!block && section_id == BDB_LVDS_LFP_DATA_PTRS) { > > + temp_block = generate_lfp_data_ptrs(i915, bdb); > > + if (temp_block) > > + block = temp_block + 3; > > + } > > if (!block) > > return; > > > > @@ -331,12 +459,16 @@ init_bdb_block(struct drm_i915_private *i915, > > > > entry = kzalloc(struct_size(entry, data, max(min_size, block_size) + 3), > > GFP_KERNEL); > > - if (!entry) > > + if (!entry) { > > + kfree(temp_block); > > return; > > + } > > > > entry->section_id = section_id; > > memcpy(entry->data, block - 3, block_size + 3); > > > > + kfree(temp_block); > > + > > drm_dbg_kms(&i915->drm, "Found BDB block %d (size %zu, min size %zu)\n", > > section_id, block_size, min_size); > > -- > Jani Nikula, Intel Open Source Graphics Center -- Ville Syrjälä Intel