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([2600:8803:e7e4:1d00:d77b:6acc:2ad1:8ff]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-734f6b5f68asm2146882a34.66.2025.05.21.07.12.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 21 May 2025 07:12:05 -0700 (PDT) Message-ID: <14a80484-5cfa-49bb-9608-12f25a113b23@baylibre.com> Date: Wed, 21 May 2025 09:12:05 -0500 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 3/3] pwm: axi-pwmgen: add support for external clock To: =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= Cc: Michael Hennerich , =?UTF-8?Q?Nuno_S=C3=A1?= , Trevor Gamblin , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-pwm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250520-pwm-axi-pwmgen-add-external-clock-v1-0-6cd63cc001c8@baylibre.com> <20250520-pwm-axi-pwmgen-add-external-clock-v1-3-6cd63cc001c8@baylibre.com> <0dd1a97e-ff7c-4d09-b18e-5df9944488c6@baylibre.com> Content-Language: en-US From: David Lechner In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 5/21/25 8:54 AM, Uwe Kleine-König wrote: > Hello David, > > On Wed, May 21, 2025 at 08:19:51AM -0500, David Lechner wrote: >> On 5/21/25 4:22 AM, Uwe Kleine-König wrote: >>> Can you achieve the same effect with the (IMHO slightly nicer but >>> hand-crafted) following patch: >>> >>> ddata = pwmchip_get_drvdata(chip); >>> ddata->regmap = regmap; >>> >>> - clk = devm_clk_get_enabled(dev, NULL); >>> - if (IS_ERR(clk)) >>> - return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n"); >>> + axi_clk = devm_clk_get_enabled(dev, "axi"); >>> + if (IS_ERR(axi_clk)) >>> + return dev_err_probe(dev, PTR_ERR(axi_clk), "failed to get axi clock\n"); >>> >>> + clk = devm_clk_get_enabled_optional(dev, "ext"); >>> + if (IS_ERR(clk)) >>> + return dev_err_probe(dev, PTR_ERR(clk), "failed to get ext clock\n"); >>> + } >> >> The trouble with this is that it would not work with existing .dtbs >> that don't have clock-names set. I think it would need to be more like this: >> >> >> axi_clk = devm_clk_get_enabled(dev, NULL); >> if (IS_ERR(axi_clk)) >> return dev_err_probe(dev, PTR_ERR(axi_clk), "failed to get axi clock\n"); >> >> clk = devm_clk_get_enabled_optional(dev, "ext"); >> if (IS_ERR(clk)) >> return dev_err_probe(dev, PTR_ERR(clk), "failed to get ext clock\n"); >> >> if (!clk) >> clk = axi_clk >> > > If there are no clock-names, the parameter is ignored. (I didn't test, > only quickly checked the code.) So passing "axi" instead of NULL should > work and yield a more robust solution. > > Best regards > Uwe I didn't know that. So with your suggestion, I guess we would get/enable the same clock twice. I guess that doesn't hurt anything. I will try it.