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Date: Wed, 1 Nov 2017 23:33:34 +0530 From: Jassi Brar <jassisinghbrar@...il.com> To: Sudeep Holla <sudeep.holla@....com> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, Arnd Bergmann <arnd@...db.de>, Bjorn Andersson <bjorn.andersson@...aro.org> Subject: Re: [PATCH] mailbox: add support for doorbell/signal mode controllers On Wed, Nov 1, 2017 at 10:02 PM, Sudeep Holla <sudeep.holla@....com> wrote: > > Such controllers don't need to transmit any data, they just transmit > the signal. In such controllers the data pointer passed to > mbox_send_message is passed to client via it's tx_prepare callback. > Controller doesn't need any data to be passed from the client. > Some controllers need a non-zero value written to a register in order to trigger the signal. That register is visible to the remote. While the data/packet is setup during tx_prepare() callback. You are overlooking this class of doorbell controllers. > > This is rough idea I have on extending mailbox interface to support > the doorbell requirements. > What doorbell requirements does the api not support? QComm's APCS IPC is what you call a "doorbell" controller and is already supported by the API. It could run SCMI even easier than MHU (your controller). > The new API send_signal will eliminate the > issue Jassi has explained in earlier discussion with respect to generic > message format using Rockchip example. > Sorry I don't see how. Please explain how can send_signal() api be used by, say, rockchip to support SCMI? I am not convinced we should clone an api just so that a client driver becomes simpler. Esp when it shifts, and not avoid, the additional code (to support the client) onto the provider side. Thanks.
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