From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6C26B261B8D; Fri, 10 Jul 2026 05:52:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783662730; cv=none; b=AALTy+rcKCe8lyLrJZc/HfHeTI6hFGwOdSpWEo9KoK3SeQZitCkaqHE/O1ZjXH2vsOUIcJHEJpbGeT/I6UBDPlgGmmm5ztzRysvvk042NVMCKLZyyrKzINz1xaTKcEZppK1G2rLAhd2YXEMqQCq7P+GkqPf8g/PKe4IlaWmQeDs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783662730; c=relaxed/simple; bh=C4dNNoFjTmPVDTd4umr8f7jmGd8315uAllp4/LlblxE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NGh/ltMk3Aytxtjo0p2Q5dQOP22ozXNmBRtOF+ovK1R38gC78I9ny/bIxqUuOBJK+Sto0iU+LVUICwO5Ad2rtSTT5g66MfkdejeA0DVaOIFVP6SaMmVOmCJrHN+UhQjaOH6jDcN94zXyBGcieKwEOlWcHBIRQsOpfpX1AtQW4aw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aIOX9Shj; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aIOX9Shj" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id 785011F00A3A; Fri, 10 Jul 2026 05:52:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783662729; bh=ZlU/SLfr9dTR0mdUitfTL77FTvnZBZpyDlOZV2Imu08=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=aIOX9ShjNelV0k+BMzoYK183zFCk/u95tFkL52ITZ0QIvUUWuA7Ee4APMimULIqP0 yf+RzAf2uuh2tjmx92xYZsTW5kQPv2y0lUWzcH5ECLppWnLopoLlLiFDe/kykGsj1E xwYAVBFjiLxTGEzLddV7KP1bKYyzSWLpuVOXn9bmJFs6kuR4xjizEl7TFYR9AGi+1w HmlNjAyuI+ROhxEqzVuk7KDBMGr47KjqRl8O7M0GfmroZngfJt8s5NnyjrSqs8WTa7 5qcbvTiQiwN1MZdU7RHDbWl2votRN3czdFlJstJwRHPeDj5TsBy7xT1eFhdZuN5x1D lezXDmL3US5rw== Date: Fri, 10 Jul 2026 07:52:06 +0200 From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= To: Keguang Zhang Cc: Binbin Zhou , linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] pwm: loongson: Fix low pulse buffer register handling Message-ID: References: <20260626-pwm-loongson-fix-v2-0-5492db953879@gmail.com> <20260626-pwm-loongson-fix-v2-1-5492db953879@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@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="pg2hkufpcicibmwc" Content-Disposition: inline In-Reply-To: --pg2hkufpcicibmwc Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v2 1/2] pwm: loongson: Fix low pulse buffer register handling MIME-Version: 1.0 Hello, On Thu, Jul 09, 2026 at 03:25:38PM +0800, Keguang Zhang wrote: > On Mon, Jul 6, 2026 at 4:00=E2=80=AFPM Uwe Kleine-K=C3=B6nig wrote: > > > - /* duty & period have a max of 2^32, so we can't overflow */ > > > - state->duty_cycle =3D DIV64_U64_ROUND_UP((u64)duty * NSEC_PER_S= EC, ddata->clk_rate); > > > + /* low & period have a max of 2^32, so we can't overflow */ > > > + state->duty_cycle =3D DIV64_U64_ROUND_UP((u64)(period - low) * = NSEC_PER_SEC, ddata->clk_rate); > > > > What happens if low > period? >=20 > pwm_state_valid() in drivers/pwm/core.c ensures that duty_cycle <=3D > period before the framework calls the driver's .apply(). Since this > driver always programs low =3D period - duty, low cannot exceed period > when configured through the PWM framework. But this is only the case when .get_state() is called after the hardware was programmed by Linux. The function should also work for the state the bootloader left the hardware in. Best regards Uwe --pg2hkufpcicibmwc Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEP4GsaTp6HlmJrf7Tj4D7WH0S/k4FAmpQiIMACgkQj4D7WH0S /k6sKwf/bnIBymcZ/fJgylLmT3nJ/s8EtYF02hfFrxZA6aOX62BqWC4jM8sqBrAr LF2Rvnyhs0JAgaqYUE75gRscrS8oLJgMjKpFQ/0PIPmsukVRRTKq6QRDKh4zRRF7 nOQ62cu1jzqjytxEX3rtoLMmCuzuNd9FhrgSIV3QYixkXAhxRnMU10BvHl6mKgYX WDtMf0p2Yr0yJcvOn57zs+buCh9toA2cS4KFy36mSvyubipQRxNSrQ+gdzT7E+5q Ft6ZZ4dQuJKsHOkrCyhflr5dG4PHXB9vpA7boSFZYfmtvHs3M08FRTl9k7I5SN8t EN70pwOc/dAenzNuCjiaqKKBX0XHFw== =NEj/ -----END PGP SIGNATURE----- --pg2hkufpcicibmwc--