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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:56254) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uZYo3-0008JZ-0r; Wed, 09 Jul 2025 18:42:07 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.96) (envelope-from ) id 1uZYnv-0002pD-1X; Wed, 09 Jul 2025 18:41:59 +0100 Date: Wed, 9 Jul 2025 18:41:59 +0100 From: "Russell King (Oracle)" To: lizhe Cc: Andrew Lunn , andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, vladimir.oltean@nxp.com, maxime.chevallier@bootlin.com, netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: Re: Re: Re: Re: [PATCH] net: stmmac: Support gpio high-level reset for devices requiring it Message-ID: References: <20250708165044.3923-1-sensor1010@163.com> <52b71fe7-d10a-4680-9549-ca55fd2e2864@lunn.ch> <5c7adfef.1876.197ece74c25.Coremail.sensor1010@163.com> <5bb49dc0.6933.197ee28444e.Coremail.sensor1010@163.com> <4cfb4aab.9588.197eefef55f.Coremail.sensor1010@163.com> <2352b745.a454.197efeef829.Coremail.sensor1010@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2352b745.a454.197efeef829.Coremail.sensor1010@163.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250709_104229_614418_1CB85F06 X-CRM114-Status: GOOD ( 17.25 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jul 10, 2025 at 12:05:05AM +0800, lizhe wrote: > Hi， > > > > if i add the following code to this function, the gpio outputs a high level > > without this code, it outputs a low level, > the function currently drivers the reset GPIO to a low state, failing to account > > for devices requiring an active-high reset. > > > > > i invited our hardware engineer to measure the voltage level on this GPIO pin, > > without adding this code, the voltage at this GPIO pin remains at 0V > > > > > + int current_value; > > > > > + keep_high = device_property_read_bool(priv->device, > > + "snps,reset-keep-high"); > > + if (keep_high) { > > + gpiod_set_value_cansleep(reset_gpio, 1); > > + current_value = gpiod_get_value_cansleep(reset_gpio); > > + pr_info("current_value: %d\n", current_value); > > + } > > in the RK3588 system, i am using ,there are many DTS node configured link this: > > snps, reset-gpio = <&gpioX RK_PXX GPIO_ACTIVE_HIGH>; > All of them correctly parse the GPIO pin's state are described in the DTS > I'm wondering at this point whether the problem here is one of mis-understanding the engineering terminology. Look at the below using a fixed-width font: Active-high reset: _____/^^^^^^^^\____ Active-low reset: ^^^^^\________/^^^^ | reset | |asserted| So, an active high reset needs to be logic low in order for the device to function. An active low reset needs to be logic high for the device to function. You seem to be wanting to tell the kernel that you have an active high reset, and expect it to be logic high when you want it to be active. That is *not* an active high reset. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!