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 78C7C371CE2; Tue, 17 Mar 2026 09:42:41 +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=1773740561; cv=none; b=KjBz+WzjsVm3LZC3o/FJzkP9ColLmdKAmws8QkmtsFdJne+bwplxmB56BWMnnC9IcGZpIWOacrhd/QbwWisXIMtAkJmunfaPqmGyb0ZYx8fBriaBEOAJFyp0D8nxBPCC8pDNZW+T8mdq2zmfbkEFv1pwFa8UXgTeHo1/pcsbSO4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773740561; c=relaxed/simple; bh=GOgDglq38ZJQbFD9CQRV0CUd4xxBjr9NAQ/XAYazlMo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ErI1GdMnuzZTU2LxGzDmwlVBj8DxNZiYxDSSTqIJBSqQROQielgCCZOmaZl7tgcOOtN69fJzFw9XZJ3RqnOwhqS9rO8y8Dsboqy/1L90Xa2B2gZlB8Tk6nQm5d8exrVOYyi8XRCpal7nA6Je2Rr5zjyyV0GjvgoqJW4omg1aAIw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rC4YnDEJ; 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="rC4YnDEJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 919DDC4CEF7; Tue, 17 Mar 2026 09:42:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773740561; bh=GOgDglq38ZJQbFD9CQRV0CUd4xxBjr9NAQ/XAYazlMo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rC4YnDEJjVyIL0EuKnWVKCgniluJiL4dfnUiWcyufq13pI1ifp/An3oC+2yV94Zo1 a8k/e3BEGNccINq+Fpgq2tEwUNIFkD/Xm1QkEhHpEAfcbQK3JGJQY9svWUEJuwusPC 3Q1YBy0orWspi+im23jtcsBLXQqhSHuqW0rSdB6e/B6fDQxaG5aPJKA9GITFdVCehc bCJrxKFqGFKWRiAHHk0qXCk9QQQlmuKomkhPNsBpNBvbULb9WaGLaH6mZJG5TQ02c6 u7hmDVkGR2rh3f6oejFh+Zvx/0Y2EWHErXo3DNXN0gSAMGuQ3vNPlyofkRzW4Q5KhK 0gjy/jKGtncUg== Date: Tue, 17 Mar 2026 10:42:38 +0100 From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= To: Xuyang Dong Cc: Krzysztof Kozlowski , robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, ben-linux@fluff.org, ben.dooks@codethink.co.uk, p.zabel@pengutronix.de, linux-pwm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, ningyu@eswincomputing.com, linmin@eswincomputing.com, xuxiang@eswincomputing.com, wangguosheng@eswincomputing.com, pinkesh.vaghela@einfochips.com Subject: Re: [PATCH v2 1/2] dt-bindings: pwm: dwc: add reset optional Message-ID: References: <20260306093000.2065-1-dongxuyang@eswincomputing.com> <20260306093058.2126-1-dongxuyang@eswincomputing.com> <20260307-charming-shrewd-mantis-54bf9f@quoll> <2d4f2cf9.3fe0.19cd1e8df20.Coremail.dongxuyang@eswincomputing.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="zgwzkypnenelndf5" Content-Disposition: inline In-Reply-To: <2d4f2cf9.3fe0.19cd1e8df20.Coremail.dongxuyang@eswincomputing.com> --zgwzkypnenelndf5 Content-Type: text/plain; protected-headers=v1; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v2 1/2] dt-bindings: pwm: dwc: add reset optional MIME-Version: 1.0 Hello, On Mon, Mar 09, 2026 at 05:23:45PM +0800, Xuyang Dong wrote: > The DesignWare PWM controller provides separate reset signals dedicated=A0 > to each clock domain, as specified in the hardware documentation.=A0 > Without asserting and deasserting these resets during probe, the PWM=A0 > output may remain in an undefined state after system reboot. Note there is an additional difficulty: A usual wish for machines with a display is that the bootloader sets up a splash screen that is smoothly taken over by Linux during boot. A reset of the PWM driving the backlight then most probably results in a short dark display which doesn't qualify for smooth. So if you have a way to distinguish between "random state after power-on" and "already programmed by the bootloader" this would be great. Best regards Uwe --zgwzkypnenelndf5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEP4GsaTp6HlmJrf7Tj4D7WH0S/k4FAmm5IgsACgkQj4D7WH0S /k76Hwf+Is79BfN2t2mk4AmX4znPAvPkJFzQZ64CCr/XjKKXcSFLUKH2iCjQgHgV +w3kpzNO55hWMfbAQR3Pt7FYHLXOsPA5qxxMaKqJoQDFkCtS1Qwi0zQCWnIPio+p ujYxrJeaBHmrcy71VCG0sSMxIErrHuELuLPtJ7BVeeAXQehQP297HtQXYReNQkkt PTaBW0TwN8a7FJXgWGPsl1nN/nLD2LPG2cKrKdpNZR0dDc+5evZj8K6KGF5aiQnN CKXMw93ewCQZQKioRUeNd0ahD6RcOmbDCRqOSA/Gy5AaPY5J0tSGaZoQCyKnG2Uf oS9LE9hEMZasEwEsV+bskVXqTumFqg== =ftGc -----END PGP SIGNATURE----- --zgwzkypnenelndf5--