From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ixit.cz (ixit.cz [84.42.129.46]) (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 D7FAE42F709; Mon, 21 Sep 2026 11:11:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=84.42.129.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789989085; cv=none; b=itIPDjksUHf+xcxfrRCxs5YOepeNzM2LHJ/8OFjdf+f5MrouDEyenG/UQbWzNShnGrdR2MhI1wJ6y6jH/LMyoMIJVzyp3ipCApgtQmGiEP2jPXwBU5pmaebUxI3Du2eHDoNXPPyR/XWL3/UMSmRTqtdec9OjGqwW4/oUyaUfEAI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789989085; c=relaxed/simple; bh=KVmw4/iCMEr46CN6E/02QkIGZ5qIw/ifaBePmcgBqkE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nC0nHy9uGmaoLhqwYXlELYAB1NNHeMVz5FpRBGffWfcaSrn3rW/Icyyb8h/xeY3bEQ9qv8r71XK/rWNbLbZkXCxxFymgem8pzjDbY5xqAV1KuhMDaQfYL81e6yxIbatbN9iUNz8o8gC35m5lwW3GhB/NTyBLSWlgQ7v0tsPb+go= ARC-Authentication-Results:i=1; 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t=1789989079; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=IecxrbI1Oxnp6UQdEsBFcFLuXx/aPYWQ+14ndTQaXH8=; b=IuzV5ABlF2Hqnl2UjIxaHjpRF7887QNhwI1nyJit5VuxSJkEEU5y+SwAiglo02WsfREJd6 yOezSg/vXNFecdwryc1fl0z89Ge8pplzks8FFj9ntdMkygeeko5gm5/e5+1usvVvyUsq2t ysSEn8nmOgPKXlxwPqEbAkdySsg5xdM= Message-ID: <426b6aeb-578f-43ee-865d-30e69b7bb2f2@ixit.cz> Date: Mon, 21 Sep 2026 13:11:18 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/4] backlight: qcom-wled: Fix WLED3 brightness register stride To: Konrad Dybcio , Lee Jones , Daniel Thompson , Jingoo Han , Helge Deller , Kiran Gunda , Marco Mattiolo , =?UTF-8?B?QmFybmFiw6FzIEN6w6ltw6Fu?= Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org, Joel Selvaraj , stable@vger.kernel.org References: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@ixit.cz> <20260921-qcom-wled-backlight-v4-2-bab8c7ef73cb@ixit.cz> <22355625-a2ea-4b6e-99b3-65cf93ac8034@oss.qualcomm.com> Content-Language: en-US, cs-CZ From: David Heidelberg Autocrypt: addr=david@ixit.cz; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 21/09/2026 13:08, Konrad Dybcio wrote: > On 9/21/26 12:46 PM, David Heidelberg via B4 Relay wrote: >> From: David Heidelberg >> >> WLED3 has a 16-bit brightness register pair per string, at 0x40 + 2*n, >> which is what the pm8941-wled driver wrote to: >> >> rc = regmap_bulk_write(wled->regmap, >> wled->addr + WLED3_CTRL_REG_VAL_BASE + 2 * i, >> v, 2); >> >> The restructuring for WLED3 turned that into WLED3_SINK_REG_BRIGHT(n), >> defined as 0x40 + n, so the two byte writes for consecutive strings >> overlap: string 1 overwrites the MSB of string 0 with its own LSB, and >> with the default three strings only string 1 ends up with the requested >> value. >> >> Use the 2 byte stride. >> >> Fixes: 775d2ffb4af6 ("backlight: qcom-wled: Restructure the driver for WLED3") >> Cc: stable@vger.kernel.org >> Assisted-by: LLM >> Signed-off-by: David Heidelberg >> --- >> drivers/video/backlight/qcom-wled.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c >> index 2281007bdd459..f452d328997ad 100644 >> --- a/drivers/video/backlight/qcom-wled.c >> +++ b/drivers/video/backlight/qcom-wled.c >> @@ -54,17 +54,17 @@ >> #define WLED3_SINK_REG_SYNC 0x47 >> #define WLED3_SINK_REG_SYNC_CLEAR 0x00 >> >> #define WLED3_SINK_REG_CURR_SINK 0x4f >> #define WLED3_SINK_REG_CURR_SINK_MASK GENMASK(7, 5) >> #define WLED3_SINK_REG_CURR_SINK_SHFT 5 >> >> /* WLED3 specific per-'string' registers below */ >> -#define WLED3_SINK_REG_BRIGHT(n) (0x40 + n) >> +#define WLED3_SINK_REG_BRIGHT(n) (0x40 + (n * 0x2)) > > Ideally n would be wrapped in its own parentheses (doesn't > checkpatch warn against that?) Yeah it does, thou not sure it make sense here. If needed, I'll send another version with it... :) Thanks David > > Reviewed-by: Konrad Dybcio > > Konrad