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Mon, 14 Jul 2025 11:40:14 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: T7a47ae1d7bea40f2 Date: Mon, 14 Jul 2025 17:39:53 +0200 From: "Arnd Bergmann" To: "Jassi Brar" , "Guomin Chen" Cc: "Rob Herring" , krzk+dt@kernel.org, "Conor Dooley" , "Catalin Marinas" , "Will Deacon" , "Peter Chen" , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, cix-kernel-upstream@cixtech.com, "Marc Zyngier" , "Sudeep Holla" , "Kajetan Puchalski" , "Enric Balletbo" , "Gary Yang" , "Lihua Liu" Message-Id: <6b5f38f7-0557-483b-9252-cfade7a24cf5@app.fastmail.com> In-Reply-To: References: <20250609031627.1605851-1-peter.chen@cixtech.com> <20250609031627.1605851-6-peter.chen@cixtech.com> Subject: Re: [PATCH v9 5/9] mailbox: add CIX mailbox driver Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Sun, Jul 13, 2025, at 19:00, Jassi Brar wrote: > On Tue, Jul 8, 2025 at 8:54=E2=80=AFAM Guomin chen wrote: > .... >> > > +/* [0~7] Fast channel >> > > + * [8] doorbell base channel >> > > + * [9]fifo base channel >> > > + * [10] register base channel >> > > + */ >> > > +#define MBOX_FAST_IDX 7 >> > > +#define MBOX_DB_IDX 8 >> > > +#define MBOX_FIFO_IDX 9 >> > > +#define MBOX_REG_IDX 10 >> > > +#define CIX_MBOX_CHANS 11 >> > > + >> > if it is not really a single controller owning different channels, >> > maybe implement only what you currently use. >> > >> As mentioned in the previous email, a single controller can support >> multiple different channels. >> > OK. I am not too worried about having all variants in one driver esp > when it is manageable and share the code. > Unless I am overlooking something. Arnd? My main worry here is that the types are all quite different: while the doorbell and fast mailboxes are what a lot of other drivers have, the FIFO mode does not seem to be a good fit for the mailbox subsystem but instead looks like a more generic firmware interface with variable length messages. For those, I think a higher-level driver with fixed data structures passed through the hardware interface seems more appropriate. Are there any other mailbox drivers that just use the mailbox to tunnel variable-length messages? Arnd=20