There might be hardware configurations where 64-bit data accesses to NVMe registers are not supported properly. This patch removes the readq/writeq so always two 32-bit accesses are used to read/write 64-bit NVMe registers, similarly as it is done in Linux kernel.
This patch fixes operation of NVMe devices on RPi4 Broadcom BCM2711 SoC based board, where the PCIe Root Complex, which is attached to the system through the SCB bridge.
Even though the architecture is 64-bit the PCIe BAR is 32-bit and likely the 64-bit wide register accesses initiated by the CPU are not properly translated to a sequence of 32-bit PCIe accesses. nvme_readq(), for example, always returns same value in upper and lower 32-bits, e.g. 0x3c033fff3c033fff which lead to NVMe devices to fail probing.
This fix is analogous to commit 8e2ab05000ab ("usb: xhci: Use only 32-bit accesses in xhci_writeq/xhci_readq").
Cc: Sylwester Nawrocki s.nawrocki@samsung.com Cc: Nicolas Saenz Julienne nsaenzjulienne@suse.de Cc: Matthias Brugger mbrugger@suse.com Reviewed-by: Stefan Roese sr@denx.de Reviewed-by: Bin Meng bmeng.cn@gmail.com Signed-off-by: Stefan Agner stefan@agner.ch ---
Changes in v2: - Fix subject and message to reflect NVMe change
drivers/nvme/nvme.h | 8 -------- 1 file changed, 8 deletions(-)
diff --git a/drivers/nvme/nvme.h b/drivers/nvme/nvme.h index 0e8cb221a7..aa4b3bac67 100644 --- a/drivers/nvme/nvme.h +++ b/drivers/nvme/nvme.h @@ -535,28 +535,20 @@ struct nvme_completion { */ static inline u64 nvme_readq(__le64 volatile *regs) { -#if BITS_PER_LONG == 64 - return readq(regs); -#else __u32 *ptr = (__u32 *)regs; u64 val_lo = readl(ptr); u64 val_hi = readl(ptr + 1);
return val_lo + (val_hi << 32); -#endif }
static inline void nvme_writeq(const u64 val, __le64 volatile *regs) { -#if BITS_PER_LONG == 64 - writeq(val, regs); -#else __u32 *ptr = (__u32 *)regs; u32 val_lo = lower_32_bits(val); u32 val_hi = upper_32_bits(val); writel(val_lo, ptr); writel(val_hi, ptr + 1); -#endif }
struct nvme_bar {