Hi, On 02/28/18 03:16, Jassi Brar wrote: > On Wed, Feb 28, 2018 at 7:57 AM, Samuel Holland <samuel@xxxxxxxxxxxx> wrote: > .... > >> +/* >> + * The message box hardware provides 8 unidirectional channels. As the mailbox >> + * framework expects them to be bidirectional >> > That is incorrect. Mailbox framework does not require a channel to be > TX and RX capable. Sorry, it would be more accurate to say that the intended mailbox _client_ expects the channels to be bidirectional. > You should expose each channel as per its physical capability, let the > client configure it for direction (if its bidirectional) and acquire > separate channels for RX and TX if it needs to. Is there any way for the mailbox framework to inform the client that a channel is uni/bidirectional? Or if the channel supports RX/TX specifically? I couldn't find any. It looks like all of the clients assume one case or the other, based on the hardware they were initially designed to support. For example arm_scpi expects one channel per client, while ti_sci and st_remoteproc expect two separate RX and TX channels per client. Since there's no API for the client to know the hardware properties, modifying arm_scpi to support unidirectional mailbox channels would break support for all existing bidirectional mailboxes. To expose the physical channels individually, there would need to be an API to: a) Determine if a mailbox channel supports unidirectional or bidirectional operation. b) If a channel is unidirectional, determine which direction(s) it supports. c) If a unidirectional channel supports both directions, configure which direction it should run in. Since that API doesn't currently exist, I wrote the driver to match what the intended client expected (as all other mailbox controller drivers currently do). > Cheers! Regards, Samuel -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
