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Tue, 10 Dec 2024 16:15:21 -0800 (PST) Received: from google.com ([2620:15c:9d:2:adc0:9d23:2d12:1822]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2ef27078b03sm13470360a91.38.2024.12.10.16.15.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Dec 2024 16:15:20 -0800 (PST) Date: Tue, 10 Dec 2024 16:15:18 -0800 From: Dmitry Torokhov To: Charles Keepax Cc: broonie@kernel.org, linus.walleij@linaro.org, brgl@bgdev.pl, linux-gpio@vger.kernel.org, linux-spi@vger.kernel.org, patches@opensource.cirrus.com Subject: Re: [PATCH 1/3] gpio: swnode: Add ability to specify native chip selects for SPI Message-ID: References: <20240326141108.1079993-1-ckeepax@opensource.cirrus.com> <20240326141108.1079993-2-ckeepax@opensource.cirrus.com> Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240326141108.1079993-2-ckeepax@opensource.cirrus.com> On Tue, Mar 26, 2024 at 02:11:06PM +0000, Charles Keepax wrote: > SPI devices can specify a cs-gpios property to enumerate their > chip selects. Under device tree, a zero entry in this property can > be used to specify that a particular chip select is using the SPI > controllers native chip select, for example: > > cs-gpios = <&gpio1 0 0>, <0>; > > Here the second chip select is native. However, when using swnodes > there is currently no way to specify a native chip select. The > proposal here is to register a swnode_gpio_undefined software node, > that can be specified to allow the indication of a native chip > select. For example: > > static const struct software_node_ref_args device_cs_refs[] = { > { > .node = &device_gpiochip_swnode, > .nargs = 2, > .args = { 0, GPIO_ACTIVE_LOW }, > }, > { > .node = &swnode_gpio_undefined, > .nargs = 0, > }, > }; I am sorry, I am very late to the party, but wouldn't it all work by simply setting ".node" to NULL? As far as I can see we have in software_node_get_reference_args(): ... if (index * sizeof(*ref) >= prop->length) return -ENOENT; ref_array = prop->pointer; ref = &ref_array[index]; refnode = software_node_fwnode(ref->node); if (!refnode) return -ENOENT; if ref->node is NULL then software_node_fwnode(ref->node) will return NULL and we'll get -ENOENT which will bubble up to gpiod_get_index_optional() in SPI core. Thanks. -- Dmitry