Hi, during xchg_single 32 bits will be sent and received: 2x32 bits / 10 Microseconds = 6.4MHz Clock. Hence, a 10 Microseconds timeout will break SPI communication for boards with SPI frequencies less then 6.4MHz. On some boards spi-max-frequency is limited due to improper communication at higher frequencies, e.g. for the kindle4 it is 1MHz and there also exists one board with 100kHz. Before sending a patch calculating the timeout from spi-max-frequency, is 640 Microseconds (to fit imx28-cfa10049.dts 100kHz) acceptable? Regards, Alexander On Wed, 2 Aug 2017, Uwe Kleine-König wrote: > Hello, > > during bringup of an i.MX7 board I am faced with cspi_2_3_xchg_single not > returning. I don't know yet why this happens, but with this patch set it at least > doesn't block barebox. > > I didn't test on a working board, maybe the timeout (10 ?s) I chose is too tight? > > Best regards > Uwe > > Uwe Kleine-K?nig (2): > spi: imx: add error checking > spi: imx: add timeout to xchg_single > > drivers/spi/imx_spi.c | 105 ++++++++++++++++++++++++++++++++++---------------- > 1 file changed, 72 insertions(+), 33 deletions(-) > > -- > 2.11.0 > > >
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