On Wed, Aug 8, 2018 at 8:04 PM, Mikko Perttunen <cyndis@xxxxxxxx> wrote: > > > On 08/08/2018 05:10 PM, Jassi Brar wrote: >> >> On Wed, Aug 8, 2018 at 5:08 PM, Mikko Perttunen <cyndis@xxxxxxxx> wrote: >>> >>> >>> >>> On 04.08.2018 13:45, Mikko Perttunen wrote: >>>> >>>> >>>> On 08/03/2018 03:54 PM, Jassi Brar wrote: >>>>> >>>>> >>>>> On Mon, Jul 2, 2018 at 5:10 PM, Mikko Perttunen <mperttunen@xxxxxxxxxx> >>>>> wrote: >>>>>> >>>>>> >>>>>> Add a new TXDONE option, TXDONE_BY_BLOCK. With this option, the >>>>>> send_data function of the mailbox driver is expected to block until >>>>>> the message has been sent. The new option is used with the Tegra >>>>>> Combined UART driver to minimize unnecessary overhead when >>>>>> transmitting >>>>>> data. >>>>>> >>>>> 1) TXDONE_BY_BLOCK flag :- >>>>> Have you tried setting the flag >>>>> mbox_chan->mbox_client->tx_block >>>>> ? >>>> >>>> >>>> >>>> No - I suppose I should have done that. I'm a bit concerned about >>>> overhead >>>> as send_data may be called thousands of times per second, so I tried to >>>> make >>>> it as close as possible to the downstream driver that just pokes the >>>> mailbox >>>> register directly. >>> >>> >>> >>> I tried using polling in the mailbox framework. Some printing is done >>> from >>> atomic context so it seems tx_block cannot be used - >>> wait_for_completion_timeout understandably does not work in atomic >>> context. >>> I also tried without tx_block, in which case I got some horribly garbled >>> output, but "Try increasing MBOX_TX_QUEUE_LEN" was readable there. >>> >>> Any opinions? >>> >> The problems arise because your hardware (SM) supports TXDONE_BY_POLL, >> but your client drives it by TXDONE_BY_ACK because the older DB >> channels are so. >> >> Please populate SM channels as a separate controller than DB. >> The DB controller, as is, run by ACK method. >> The SM controller should be run by polling, i.e, set txdone_poll = >> true and the poll period small enough. The virtual tty client driver >> should be able to safely set tx_block from appropriate context. >> > > Sorry, I should have clarified that I already split up the controllers. The > SM controller has txdone_poll = true. I didn't adjust txpoll_period so I > guess it's zero. > Can you please share your code (controller and client) ? Maybe offline if you wish. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
