Messages in this thread | | | From | Kumar Gala <> | Subject | Re: [spi-devel-general] [PATCH][2.16.17-rc1-mm2] spi: Added spi master driver for Freescale MPC83xx SPI controller | Date | Mon, 10 Apr 2006 15:22:38 -0500 |
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On Apr 10, 2006, at 3:03 PM, Vitaly Wool wrote:
> Hi, > > Kumar Gala wrote: > >> +irqreturn_t mpc83xx_spi_irq(s32 irq, void *context_data, >> + struct pt_regs * ptregs) >> +{ >> + struct mpc83xx_spi *mpc83xx_spi = context_data; >> + u32 event; >> + irqreturn_t ret = IRQ_NONE; >> + >> + /* Get interrupt events(tx/rx) */ >> + event = mpc83xx_spi_read_reg(&mpc83xx_spi->base->event); >> + >> + /* We need handle RX first */ >> + if (event & SPIE_NE) { >> + u32 rx_data = mpc83xx_spi_read_reg(&mpc83xx_spi->base->receive); >> + >> + if (mpc83xx_spi->rx) >> + mpc83xx_spi->get_rx(rx_data, mpc83xx_spi); >> + >> + ret = IRQ_HANDLED; >> + } >> + >> + if ((event & SPIE_NF) == 0) >> + /* spin until TX is done */ >> + while (((event = >> + mpc83xx_spi_read_reg(&mpc83xx_spi->base->event)) & >> + SPIE_NF) == 0) >> + ; >> > This is a potentially endless loop so two questions here. > First, did you do any measurements on how long it can loop here? > The, what if a bus error occurs and this bit is never set?
In my measurements the if is never true, so we never spin.
I wasn't particular happy about the spinning for ever, wasn't sure what would be better. I need to ensure we've gotten both a TX & RX event before transmitting the next character. I'm open to suggestions on how to do this better.
>> + >> + mpc83xx_spi->count -= 1; >> + if (mpc83xx_spi->count) { >> + if (mpc83xx_spi->tx) { >> + u32 word = mpc83xx_spi->get_tx(mpc83xx_spi); >> + mpc83xx_spi_write_reg(&mpc83xx_spi->base->transmit, >> + word); >> + } >> + } else { >> + complete(&mpc83xx_spi->done); >> + } >> > So, if it's not SPIE_NF, it's not marked as HANDLED?
I wasn't sure what the best thing here was. In truth we will only get an interrupt if SPIE_NF is set so it should always be handled.
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