On 01/11/17 18:03, Jassi Brar wrote: > On Wed, Nov 1, 2017 at 10:02 PM, Sudeep Holla <sudeep.ho...@arm.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.
You are right, just right non-zero or whatever controller value to trigger the interrupt to remote. > That register is visible to the remote. While the data/packet is setup > during tx_prepare() callback. Agreed. > You are overlooking this class of doorbell controllers. > Not sure what do you mean by that ? >> >> 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). > Again agreed. But see below for reason to create this API. >> 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? > 80 writel_relaxed(msg->cmd, mb->mbox_base + MAILBOX_A2B_CMD(chans->idx)); 81 writel_relaxed(msg->rx_size, mb->mbox_base + 82 MAILBOX_A2B_DAT(chans->idx)); 83 will be replaced with writel(whatever_value_to trigger_signal, MAILBOX_A2B_CMD(chans->idx)); in its send_signal function. > 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. > It doesn't tie the data format with particular mailbox controller. send_data has void *data and the interpretation is controller specific. send_signal on the other handle can implemented by the controllers which knows how and can trigger the specific signal to the remote. -- Regards, Sudeep
