On Mon, 2018-06-04 at 12:50 +0200, Giulio Benetti wrote: > Hi, > > Il 04/06/2018 12:17, Andy Shevchenko ha scritto: > > On Fri, 2018-06-01 at 14:40 +0200, Giulio Benetti wrote: > > > Some 8250 ports only have TEMT interrupt, so current > > > implementation > > > can't work for ports without it. The only chance to make it work > > > is to > > > loop-read on LSR register. > > > > > > With NO TEMT interrupt check if both TEMT and THRE are set looping > > > on > > > LSR register. > > > --- a/drivers/tty/serial/8250/8250_dw.c > > > +++ b/drivers/tty/serial/8250/8250_dw.c > > > - int ret = serial8250_em485_init(up); > > > + int ret = serial8250_em485_init(up, false); > > > > Is true for all possible DW configured types? Or it's your > > particular > > case? > > > > I've checked on Synopsis Designware 8250 datasheet and it's not > supported. > Here is datasheet I went through: > https://linux-sunxi.org/images/d/d2/Dw_apb_uart_db.pdf > > There seems not to be TEMT interrupt, I use it under sunxi SoC and on > their datasheet(A20 for example), they don't report that interrupt > too. > So it seems to be valid for all DW configured types, anyway I don't > know > how many IP reviews there could be of that peripheral. This is an excerpt from the document you referred to: --- 8< --- 8< --- 6 TEMT R Transmitter Empty bit. If in FIFO mode (FIFO_MODE != NONE) and FIFOs enabled (FCR[0] set to one), this bit is set whenever the Transmitter Shift Register and the FIFO are both empty. If in non-FIFO mode or FIFOs are disabled, this bit is set whenever the Transmitter Holding Register and the Transmitter Shift Register are both empty. Reset Value: 0x1 --- 8< --- 8< --- If I'm reading this correctly the support is there. Or otherwise, care to point exact paragraph needs to be read and checked? > I've tried to subscribe at Synopsis to obtain latest Datasheet but it > ask me an active ID I don't have. > -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy -- 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
