From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 35204423E82 for ; Fri, 24 Jul 2026 10:39:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784889549; cv=none; b=TJUUcH7TRfP1930x1MxGtHLD0jskinADThRt+sWw6T+BaUr2Q+umXtq9stFM3/BSWz+2mRr/uNtt0tm095UDB3TIMLtGXDEBOvcZeFyR3gUZafapAunnVNjOH9YUSSyvBsxkGiOKgScDivhZYFIbewHn+RP0RUAAgZU+3Hu3TEY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784889549; c=relaxed/simple; bh=Q4yNBPRBIx1D3lqZC83Z64WgzQW1tKnH/8t6iIPIxyM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AskdmfCgRLJvP/8ztgup3ZuliXD//Sn/cnvlyeLvTb41cSJi9QrMzL/IPWUvIhRotP/DEXKjsoBMRoyfdEYmNpS//+DR7z4NJE09eyY0yJxeeYYPeU3VO7j8Oj/F7a7/g0AiMP8JIvTewU3ppxujQb9PMkaInSqf55nTiEnkA1c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=MxbYXGTv; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="MxbYXGTv" Received: from killaraus.ideasonboard.com (2001-14ba-70f3-e800--a06.rev.dnainternet.fi [IPv6:2001:14ba:70f3:e800::a06]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 25EE7524; Fri, 24 Jul 2026 12:38:01 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1784889481; bh=Q4yNBPRBIx1D3lqZC83Z64WgzQW1tKnH/8t6iIPIxyM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MxbYXGTvvs1LY8pPOAe9cfgBf0s3vlBfyUF7iqeVpG6MTHLaE0Tg1m0/0TrA/EmNt W7Y7HFsBzsTmPTOnUNqQ76in7RlheqHz2WRdlw9r0xi54JWu4b8qZS53w/5AJElHX3 NzlBsPp7RjEfdn4uffuyJ13Xrpd4qDouYRYOxTZY= Date: Fri, 24 Jul 2026 13:39:01 +0300 From: Laurent Pinchart To: phucduc.bui@gmail.com Cc: Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] drm/bridge: adv7511: use cache_only during power down Message-ID: <20260724103901.GA1051157@killaraus.ideasonboard.com> References: <20260724103235.57577-1-phucduc.bui@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260724103235.57577-1-phucduc.bui@gmail.com> On Fri, Jul 24, 2026 at 05:32:35PM +0700, phucduc.bui@gmail.com wrote: > From: bui duc phuc > > adv7511_power_on() and adv7511_power_off() restore the register state > using regcache_mark_dirty() and regcache_sync(), but nothing prevents > other code paths from accessing the registers over I2C while the chip > is powered down. Please give a detailed example of a scenario where that can happen, and make sure you can reproduce the scenario and see the issue on your hardware. > Wrap the power-down window with regcache_cache_only() to prevent direct > register accesses. It is unclear whether this is necessary or whether > it could affect the CEC or packet sub-regmaps, so send this as an RFC. > > Signed-off-by: bui duc phuc > --- > > This RFC is related to the following patch series: > https://lore.kernel.org/all/20260724100803.50169-1-phucduc.bui@gmail.com/ > > drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > index 3e470366bce0..49da1806797b 100644 > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > @@ -323,6 +323,7 @@ static void adv7511_power_off(struct adv7511 *adv7511) > __adv7511_power_off(adv7511); > if (adv7511->info->has_dsi) > adv7533_dsi_power_off(adv7511); > + regcache_cache_only(adv7511->regmap, true); > adv7511->powered = false; > } > > @@ -374,11 +375,13 @@ static void adv7511_power_on(struct adv7511 *adv7511) > /* > * Most of the registers are reset during power down or when HPD is low. > */ > + regcache_cache_only(adv7511->regmap, false); > ret = regcache_sync(adv7511->regmap); > if (ret) { > dev_err(&adv7511->i2c_main->dev, > "Failed to sync register cache: %d\n", ret); > __adv7511_power_off(adv7511); > + regcache_cache_only(adv7511->regmap, true); > return; > } > -- Regards, Laurent Pinchart