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 93541C636D7 for ; Wed, 15 Feb 2023 15:14:01 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CDACE10E133; Wed, 15 Feb 2023 15:14:00 +0000 (UTC) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by gabe.freedesktop.org (Postfix) with ESMTPS id C926010E133 for ; Wed, 15 Feb 2023 15:13:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1676474038; x=1708010038; h=from:to:subject:in-reply-to:references:date:message-id: mime-version:content-transfer-encoding; bh=NshjTsQds/MqwFHl9dux6/jp5qWrpheCLLUzPZBI41Y=; 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charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Intel-gfx] [PATCH v2] drm/i915: Reduce ELD hex dumps a bit 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, 15 Feb 2023, Ville Syrjala wrote: > From: Ville Syrj=C3=A4l=C3=A4 > > Do the ELD hexdumps only up to the last differing byte. > The rest is typically all zeroes anyway so not much point > in dumping it. > > Couldn't find anything for memcmp_diff_len() so > rolled my own. > > v2: Use semantics and function name suggested by Jani > > Cc: Jani Nikula > Signed-off-by: Ville Syrj=C3=A4l=C3=A4 Reviewed-by: Jani Nikula > --- > drivers/gpu/drm/i915/display/intel_display.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/d= rm/i915/display/intel_display.c > index 3479125fbda6..664322a58236 100644 > --- a/drivers/gpu/drm/i915/display/intel_display.c > +++ b/drivers/gpu/drm/i915/display/intel_display.c > @@ -5348,6 +5348,20 @@ pipe_config_dp_vsc_sdp_mismatch(struct drm_i915_pr= ivate *dev_priv, > } > } >=20=20 > +/* Returns the length up to and including the last differing byte */ > +static size_t > +memcmp_diff_len(const u8 *a, const u8 *b, size_t len) > +{ > + int i; > + > + for (i =3D len - 1; i >=3D 0; i--) { > + if (a[i] !=3D b[i]) > + return i + 1; > + } > + > + return 0; > +} > + > static void > pipe_config_buffer_mismatch(struct drm_i915_private *dev_priv, > bool fastset, const char *name, > @@ -5357,6 +5371,9 @@ pipe_config_buffer_mismatch(struct drm_i915_private= *dev_priv, > if (!drm_debug_enabled(DRM_UT_KMS)) > return; >=20=20 > + /* only dump up to the last difference */ > + len =3D memcmp_diff_len(a, b, len); > + > drm_dbg_kms(&dev_priv->drm, > "fastset mismatch in %s buffer\n", name); > print_hex_dump(KERN_DEBUG, "expected: ", DUMP_PREFIX_NONE, > @@ -5364,6 +5381,9 @@ pipe_config_buffer_mismatch(struct drm_i915_private= *dev_priv, > print_hex_dump(KERN_DEBUG, "found: ", DUMP_PREFIX_NONE, > 16, 0, b, len, false); > } else { > + /* only dump up to the last difference */ > + len =3D memcmp_diff_len(a, b, len); > + > drm_err(&dev_priv->drm, "mismatch in %s buffer\n", name); > print_hex_dump(KERN_ERR, "expected: ", DUMP_PREFIX_NONE, > 16, 0, a, len, false); --=20 Jani Nikula, Intel Open Source Graphics Center