On Wed, Nov 07, 2007 at 01:09:40PM +0000, Alan Cox wrote: > On Wed, 7 Nov 2007 17:10:52 +0900 > Paul Mundt <lethal@xxxxxxxxxxxx> wrote: > > By default ata_host_activate() expects a valid IRQ in order to > > successfully register the host. This patch enables a special case > > for registering polling-only hosts that either don't have IRQs > > or have buggy IRQ generation (either in terms of handling or > > sensing), which otherwise work fine. > > > > Hosts that want to use polling mode can simply set ATA_FLAG_PIO_POLLING > > and pass in a NULL IRQ handler or invalid (< 0) IRQ. > > NAK > > Zero is "no IRQ", please use that for polling not "< 0" > However, platform_get_irq() will happily return IRQ#0, and it's a valid vector on plenty of machines. NO_IRQ is also < 0 on at least FR-V, ARM, blackin, PA-RISC, some PowerPC, and even IDE. We do have some devices that are physically on IRQ#0 that otherwise work fine, they aren't ATA devices mind you, but to claim that IRQ#0 isn't a valid vector is not in line with what hardware actually does, whether it's a good idea or not. In our case the IRQ vector maps to an exception offset, which we bump down to zero. We could force an off-by-1 there so that the math that indexes IRQ#0 is bumped up one, but that entails fixing up every one of our IRQ numbers for no obvious gain. I don't really see any value in purposely crippling the range of allowable vectors for these machines. Though I don't mind switching to a NO_IRQ comparison instead of the < 0 case, so both can be handled. - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
