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[2003:e4:1f3f:4900:f22f:74ff:fe1f:3a53]) by smtp.gmail.com with ESMTPSA id z11-20020a170906074b00b00988f168811bsm2590436ejb.135.2023.10.06.02.20.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Oct 2023 02:20:05 -0700 (PDT) Date: Fri, 6 Oct 2023 11:20:03 +0200 From: Thierry Reding To: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= Cc: linux-pwm@vger.kernel.org, kernel@pengutronix.de, Bartosz Golaszewski , Andy Shevchenko Subject: Re: [PATCH v1 000/101] pwm: Fix lifetime issues for pwm_chips Message-ID: References: <20230808171931.944154-1-u.kleine-koenig@pengutronix.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="WnvlS8796A9XNP45" Content-Disposition: inline In-Reply-To: <20230808171931.944154-1-u.kleine-koenig@pengutronix.de> User-Agent: Mutt/2.2.12 (2023-09-09) Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org --WnvlS8796A9XNP45 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 08, 2023 at 07:17:50PM +0200, Uwe Kleine-K=C3=B6nig wrote: > Hello, >=20 > this series addresses the issues I reported already earlier to this > list[1]. It is based on pwm/for-next and several patches I already sent > out, too. Maybe some of these have to be reworked (e.g. Thierry already > signalled not to like the patches dropping runtime error messages) but > in the expectation that I will have to create a v2 for this series, too > and it actually fixes a race condition, I sent the patches out for > review anyhow. For the same reason I didn't Cc: all the individual > maintainers. >=20 > If you want to actually test I suggest you fetch my complete history > from >=20 > https://git.pengutronix.de/git/ukl/linux pwm-lifetime-tracking >=20 > .=20 >=20 > In the end drivers have to allocate their pwm_chip using > pwmchip_alloc(). This is important for the memory backing the pwm_chip > being able to have a longer life than the driver. Couldn't we achieve the same thing by just making sure that drivers don't use any of the device-managed APIs to do this? That seems like a slightly less intrusive way of doing things. > The motivation for this series is to prepare the pwm framework to add a > character device for each pwm_chip for easier and faster access to PWMs > from userspace compared to the sysfs API. For such an extension proper > lifetime tracking is important, too, as such a device can still be open > if a PWM disappears. As I mentioned before, I'd like to see at least a prototype of the character device patches before I merge this series. There's a whole lot of churn here and without the character device support it's hard to justify. I have a couple more detailed comments, but I'll leave those in response to some of the other patches for better context. 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