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Commit3fe9a838ec"dp8393x: Always use 32-bit accesses" set .impl.min_access_size and .impl.max_access_size to 4 to try and fix the Linux jazzsonic driver which uses 32-bit accesses. The problem with forcing the register access to 32-bit in this way is that since the dp8393x uses 16-bit registers, a manual endian swap is required for devices on big endian machines with 32-bit accesses. For both access sizes and machine endians the QEMU memory API can do the right thing automatically: all that is needed is to set .impl.min_access_size to 2 to declare that the dp8393x implements 16-bit registers. Normally .impl.max_access_size should also be set to 2, however that doesn't quite work in this case since the register stride is specified using a (dynamic) it_shift property which is applied during the MMIO access itself. The effect of this is that for a 32-bit access the memory API performs 2 x 16-bit accesses, but the use of it_shift within the MMIO access itself causes the register value to be repeated in both the top 16-bits and bottom 16-bits. The Linux jazzsonic driver expects the stride to be zero-extended up to access size and therefore fails to correctly detect the dp8393x device due to the extra data in the top 16-bits. The solution here is to remove .impl.max_access_size so that the memory API will correctly zero-extend the 16-bit registers to the access size up to and including it_shift. Since it_shift is never greater than 2 than this will always do the right thing for both 16-bit and 32-bit accesses regardless of the machine endian, allowing the manual endian swap code to be removed. Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> Fixes:3fe9a838ec("dp8393x: Always use 32-bit accesses") Message-Id: <20210705214929.17222-2-mark.cave-ayland@ilande.co.uk> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Tested-by: Finn Thain <fthain@linux-m68k.org> Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>