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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FGsxtHxS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FGsxtHxS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 030B7C433F1; Wed, 31 Jan 2024 18:43:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706726630; bh=OsBhn5fmKfi8kOG7a+u9aX/g82LydKjRXv+v9zD7SsY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=FGsxtHxSAzaOcN/5DV6z9kKZWrCxBG75yEJ+HTkJ7wz3tE7i+AkQ8lSNlubzT/Wr1 YzI0JUirmHvsyu3CjdqK2DQSJ5khkHIe7dDj2u6OflMEdGBjo7RDpqk9zezy6u+n7M 8o4klU/vOAOIp07+YLxvC4ld2aYpJiKabRHYyXs77IhQfFcJa5eg8llA+NZuYuf84t 4x92sPioNPV08CnIET+iDDUoj0PexWlAbTQtAlJ6zZtVDFm7PGFczPLR8oPtvb8N+S BOV7rZmhi5HMF0au63wBS245/ytj76g90eMbblyamoeZ055mtlfCMOVI3SDNAN2vyO /uCwIMQ/ApvKA== Date: Wed, 31 Jan 2024 12:43:47 -0600 From: Rob Herring To: Laurent Pinchart Cc: Tomi Valkeinen , Kuninori Morimoto , alsa-devel@alsa-project.org, devicetree@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-media@vger.kernel.org, linux-sound@vger.kernel.org, Uwe =?iso-8859-1?Q?Kleine-K=C3=B6nig?= , Daniel Vetter , David Airlie , Frank Rowand , Helge Deller , Jaroslav Kysela , Liam Girdwood , Maarten Lankhorst , Mark Brown , Mauro Carvalho Chehab , Maxime Ripard , Michal Simek , Saravana Kannan , Takashi Iwai , Thomas Zimmermann Subject: Re: [PATCH v2 03/13] of: property: add of_graph_get_next_endpoint_raw() Message-ID: <20240131184347.GA1906672-robh@kernel.org> References: <87fryhklhb.wl-kuninori.morimoto.gx@renesas.com> <87bk95klgc.wl-kuninori.morimoto.gx@renesas.com> <20240129130219.GA20460@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-fbdev@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: <20240129130219.GA20460@pendragon.ideasonboard.com> On Mon, Jan 29, 2024 at 03:02:19PM +0200, Laurent Pinchart wrote: > On Mon, Jan 29, 2024 at 02:29:22PM +0200, Tomi Valkeinen wrote: > > On 29/01/2024 02:54, Kuninori Morimoto wrote: > > > We already have of_graph_get_next_endpoint(), but it is not intuitive > > > to use. > > > > > > (X) node { > > > (Y) ports { > > > port@0 { endpoint { remote-endpoint = ...; };}; > > > (A1) port@1 { endpoint { remote-endpoint = ...; }; > > > (A2) endpoint { remote-endpoint = ...; };}; > > > (B) port@2 { endpoint { remote-endpoint = ...; };}; > > > }; > > > }; > > > > > > For example, if I want to handle port@1's 2 endpoints (= A1, A2), > > > I want to use like below > > > > > > A1 = of_graph_get_next_endpoint(port1, NULL); > > > A2 = of_graph_get_next_endpoint(port1, A1); > > > > > > But 1st one will be error, because of_graph_get_next_endpoint() requested > > > "parent" means "node" (X) or "ports" (Y), not "port". > > > Below are OK > > > > > > of_graph_get_next_endpoint(node, NULL); // node/ports/port@0/endpoint > > > of_graph_get_next_endpoint(ports, NULL); // node/ports/port@0/endpoint > > > > > > In other words, we can't handle A1/A2 directly via > > > of_graph_get_next_endpoint() so far. > > > > > > There is another non intuitive behavior on of_graph_get_next_endpoint(). > > > In case of if I could get A1 pointer for some way, and if I want to > > > handle port@1 things, I would like use it like below > > > > > > /* > > > * "endpoint" is now A1, and handle port1 things here, > > > * but we don't know how many endpoints port1 has. > > > * > > > * Because "endpoint" is non NULL, we can use port1 > > > * as of_graph_get_next_endpoint(port1, xxx) > > > */ > > > do { > > > /* do something for port1 specific things here */ > > > } while (endpoint = of_graph_get_next_endpoint(port1, endpoint)) > > > > > > But it also not worked as I expected. > > > I expect it will be A1 -> A2 -> NULL, > > > but it will be A1 -> A2 -> B, because of_graph_get_next_endpoint() > > > will fetch endpoint beyond the port. > > > > > > It is not useful on generic driver like Generic Sound Card. > > > It uses of_get_next_child() instead for now, but it is not intuitive, > > > and not check node name (= "endpoint"). > > > > > > To handle endpoint more intuitive, create of_graph_get_next_endpoint_raw() > > > > > > of_graph_get_next_endpoint_raw(port1, NULL); // A1 > > > of_graph_get_next_endpoint_raw(port1, A1); // A2 > > > of_graph_get_next_endpoint_raw(port1, A2); // NULL > > > > > > Signed-off-by: Kuninori Morimoto > > > --- > > > drivers/of/property.c | 26 +++++++++++++++++++++++++- > > > include/linux/of_graph.h | 2 ++ > > > 2 files changed, 27 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/of/property.c b/drivers/of/property.c > > > index 14ffd199c9b1..37dbb1b0e742 100644 > > > --- a/drivers/of/property.c > > > +++ b/drivers/of/property.c > > > @@ -667,6 +667,30 @@ struct device_node *of_graph_get_next_port(const struct device_node *parent, > > > } > > > EXPORT_SYMBOL(of_graph_get_next_port); > > > > > > +/** > > > + * of_graph_get_next_endpoint_raw() - get next endpoint node > > > > How about "of_graph_get_next_port_endpoint()"? > > We may want to also rename the existing of_graph_get_next_endpoint() > function to of_graph_next_dev_endpoint() then. It would be a tree-wide > patch, which is always annoying to get reviewed and merged, so if Rob > would prefer avoiding the rename, I'm fine with that. I think we should get rid of or minimize of_graph_get_next_endpoint() in its current form. In general, drivers should be asking for a specific port number because their function is fixed in the binding. Iterating over endpoints within a port is okay as that's usually a selecting 1 of N operation. Most cases are in the form of of_graph_get_next_endpoint(dev, NULL) which is equivalent to of_graph_get_endpoint_by_regs(dev, 0, 0). Technically, -1 instead of 0 is equivalent, but I'd argue is sloppy and wrong. I also added of_graph_get_remote_node() for this reason and cleaned a lot of these (in DRM) up some time ago. Because in the end, a driver generally just wants the remote device it is connected to and details of parsing the graph should be mostly opaque. Wouldn't something like this work for this case: #define for_each_port_endpoint_of_node(parent, port, child) \ for (child = of_graph_get_endpoint_by_regs(parent, port, -1); child != NULL; \ child = of_get_next_child(parent, child)) Rob