On Mon, Jan 21, 2013 at 01:19:23PM -0500, Matt Porter wrote: > > b) Sg segment length and numbers: Well these are capabilities, so it tells > > you what is the maximum I can do. IMO it doesn't make sense to tie it down to > > burst, width etc. For that configuration you are checking maximum. What this > > needs to return is what is the maximum length it supports and maximum number of > > sg list the h/w can use. Also if you return your burst and width capablity, then > > any client can easily find out what is the length byte value it can hold. > > Ok, so I could report the max burst size to the client, but on EDMA it's > going to be SZ_64K-1, as that's the hw limit. Max addr width would also > be the same or capped at the maximum enum the current API support of 8 > bytes. Yes IMO you should report the h/w limit and let client deduce what can be done with that h/w limit given the other parameters (burst, length etc...) > > This information is not useful to the client in my case. Only the client > knows its FIFO size, and thus the actual burst size it needs to request > as that is a value specific to the IP the client driver controls. So it > knows actual burst size and the width of that fifo transfer, because we > already support telling the dmaengine driver this info in the current > API. Your current API way is not very generic. We need to make sure it useful on other systems too. That is why it would make sense to query the DMA H/W capablities and then use it with above properties to get various parameters used for initiating a transfer, that way you dont need to set slave parameters -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
