On Wed, May 05, 2021 at 01:56:24PM +0200, Marc Kleine-Budde wrote: > For easier queuing, get rid of the worker. Directly send the can_frame > from the xmit handler. The problem is, you cannot sleep inside it. This > means, you cannot use regmap(), the only thing that works is > spi_async(). And as it's async, you can only write data via SPI, reading > doesn't make sense. Yeah, this makes things pretty tough, given that we currently have to read the next available TX buffer index before doing the writes! > Have a look at the mcp251xfd_start_xmit() function. All data structures > for the SPI messages are prepared in beforehand in > mcp251xfd_tx_ring_init_tx_obj(). The xmit function looks up the correct > data structure, converts the skb to the chip's format > mcp251xfd_tx_obj_from_skb() and then sends the data over spi. Special > care is taken of the handling of the head and tail pointers and the > stopping of the queue to avoid race conditions - see > mcp251xfd_get_tx_free(), mcp251xfd_tx_busy(), netif_stop_queue(), > netif_wake_queue(). > > Hope that helps, > Marc I'll be sure to look into it in more detail, thanks. In the meantime, your patch is working very well to mostly solve this issue :) -- Regards, Torin Cooper-Bennun Software Engineer | maxiluxsystems.com
