On Fri, May 29, 2020 at 10:46:01AM -0700, Florian Fainelli wrote: > On 5/29/20 10:43 AM, Lukas Wunner wrote: > > On Thu, May 28, 2020 at 08:58:04PM +0200, Nicolas Saenz Julienne wrote: > >> --- a/drivers/spi/spi-bcm2835.c > >> +++ b/drivers/spi/spi-bcm2835.c > >> @@ -379,6 +379,10 @@ static irqreturn_t bcm2835_spi_interrupt(int irq, > >> void *dev_id) > >> if (bs->tx_len && cs & BCM2835_SPI_CS_DONE) > >> bcm2835_wr_fifo_blind(bs, BCM2835_SPI_FIFO_SIZE); > >> > >> + /* check if we got interrupt enabled */ > >> + if (!(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_INTR)) > >> + return IRQ_NONE; > >> + > >> /* Read as many bytes as possible from FIFO */ > >> bcm2835_rd_fifo(bs); > >> /* Write as many bytes as possible to FIFO */ [...] > > Finally, it would be nice if the check would be optimized away when > > compiling for pre-RasPi4 products, maybe something like: > > > > + if (IS_ENABLED(CONFIG_ARM_LPAE) && !(cs & BCM2835_SPI_CS_INTR)) > > + return IRQ_NONE; > > Rather than keying this off ARM_LPAE or any other option, this should be > keyed off a compatible string, that way we can even conditionally pass > IRQF_SHARED to the interrupt handler if we care so much about performance.
But a compatible string can't be checked at compile time, can it? The point is that at the least the Foundation compiles and ships a separate kernel for each of the three platforms BCM2835, BCM2837, BCM2711. It's unnecessary to check whether an interrupt was actually raised if we *know* in advance that it's not shared (as is the case with kernels compiled for BCM2835 and BCM2837). Thanks, Lukas
