From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 95620A32 for ; Sun, 16 Mar 2025 11:51:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742125895; cv=none; b=qBO1SmpCBhiYhqwmb7hNOpE6VVC1idUwhV40ERZm089On80FczKa5qJ3nqxiv3mVaeckSjJ4l4jrzYSBneEc6KFF/Etw4/xp9Tv2QP7Cs3xeG9fh+vP9Xxk5SIajBA2YDw9L898ZrpBwJuO0jwh6hrEj/CPDshuHwDURYkDS2xg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742125895; c=relaxed/simple; bh=XKxESbtBn9XdX/JLhwJgPsRObgqZD16dZTIq6adwEwQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=dyik4XZPIoNK16avO0vhduIlvA6qVkel+ihjeh515OTgRNxO8XrG8TChm4Og7quh9TK3x+Z48MwRzNl+BaCtV1GucMNWbwh4M+yhvT3QvsGSfYUnT8Kg7XFR827DJNRBu2RI8xKYc4fz5iZRHUbvkjJgc0eotUVLIsEYRinEG90= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D/Wt26Y7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D/Wt26Y7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A548C4CEDD; Sun, 16 Mar 2025 11:51:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742125895; bh=XKxESbtBn9XdX/JLhwJgPsRObgqZD16dZTIq6adwEwQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=D/Wt26Y7ny0JyIbXvwK7uUeQ/nTjnIN4upeaaGw/n5/jGf//xbizxyzkHUPlw4x0t IzkK/pGbqoR0a714bamEhy9ebvQFsmbWwy2InDrysss5nrEcF5BV7hXICzwPPC6Fcb 3vPpO624EIvZ92iQEdMQX/DL57unsnqixBb1GuAzMIF4XDZDwXJ6sYX7oxm5XjmqdG HdBeuwqLKKa6veHZwxun7fXIPyCyxQjjE1KC3tzoXFaO++06nIT/4Jem5K44FgJls9 KpklNOINPz/pofq5FAjoIclyP/GCQvGoKWKpCYFIZ+WsuFEijq0ZfonT6WcmJrzKfE CexbYaEvMDROQ== Message-ID: Date: Sun, 16 Mar 2025 12:51:29 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Bug in mipi_dbi_hw_reset() causes incorrect DT entries To: Alex Lanzano , devicetree@vger.kernel.org Cc: Rob Herring , Krzysztof Kozlowski , Conor Dooley , =?UTF-8?Q?Josef_Lu=C5=A1tick=C3=BD?= References: From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 15/03/2025 16:20, Alex Lanzano wrote: > Hi all, > > There is a bug in the mipi_dbi_hw_reset() function that handles the > reset logic of the controller. Currently, it will set the reset gpio > value to 0, wait a specified time, then set the reset gpio value to 1. > > The issue with this implementation is that the MIPI DBI spec states that > the reset signal is active low. So, in order to correct for this logic, > the developer needs to incorrectly define the reset gpio as active high > in the DT. You should address it to driver and subsystem maintainers. Instead you skipped all maintainers but Cc-ed people who have nothing to do with MIPI DBI drivers in the kernel. > > Fixing the logic in the driver would cause all the displays using this > driver downstream to stop working. To mitigate this, Josef and I were > thinking about adding an additional boolean property to the DT that when > present would use the correct reset logic in the driver. And if it's not > present use the current reset logic and print out a warning that this > reset logic is deprecated. > > The overall plan would be to have this temporary fix for a few release > cycles so downstream has time to be aware of the issue and update their > DT. Eventually, we would remove the incorrect reset logic in the driver > and this addtional boolean property. That's an ABI now, so you cannot change it without affecting users. Code is from 2018 so you have plenty of users now. I did some workaround for wsa88xx speakers but that's an exception and it should not necessarily be a pattern to follow. Not sure if it the issue is worth changing considering the impact. Best regards, Krzysztof