On Mon, Feb 22, 2016 at 10:16:21AM +0100, Thomas Petazzoni wrote: > > So why should it depend on how kernel is configured? > > Because using upper_32_bits() on a 32-bits type seems wrong? You can do > a git grep for CONFIG_ARCH_DMA_ADDR_T_64BIT, and see that it is already > used in drivers/dma/sh/rcar-dmac.c, drivers/gpu/drm/tegra/dc.c or > drivers/iommu/tegra-smmu.c. > > drivers/dma/sh/rcar-dmac.c uses it for exactly the same reason as me: > they need to know if dma_addr_t is 32 bits or 64 bits, and if it's 64 > bits, then they need to take the upper 32 bits and feed them to some > register. So is the hardware capable of 32bit of 64bit? > > You don't want to check the source of interrupt? > > To protect against what? An improper MSI message that ends up firing > this interrupt for now reason? But only kernel space stuff (or > privileged code in user-space) can write to the MSI triggering > registers, so we should be able to trust that such an improper MSI > message will not arrive. Your device might go bonkers or some erranious programming does cause interrupts. Its better to be safe than sorry :) > > That being said, I can add a read of the pending descriptors number, > and if it's 0, then bail out with IRQ_NONE. Is that what you were > thinking about? Sounds good > > why BUG_ON, is the system unusable after this? > > Well, the XOR engine cannot do XOR with 0 source buffers, or with more > than MV_XOR_V2_CMD_LINE_NUM_MAX_D_BUF. > > But I see that I'm already setting max_xor in struct dma_device, so one > can assume that ->prep_dma_xor() will not be called with src_cnt == or > src_cnt > max_xor, so this BUG_ON can be removed. Okay, you should return NULL to caller if that is the case -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
