Re: [PATCH] fw_cfg: Set the max fw_cfg mem read size to 8 bytes

[Laszlo Ersek]

On 05/18/21 14:43, Xiaojuan Yang wrote:
> From: yangxiaojuan <yangxiaojuan@loongson.cn>
> 
> fw_cfg_data_read() func supports access widths from
> 1 to 8 bytes while the ops set the wrong read size.
> 
> Most arch use 8 bytes to send ram_size to bios.
> 
> Signed-off-by: yangxiaojuan <yangxiaojuan@loongson.cn>
> ---
>  hw/nvram/fw_cfg.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index 9b8dcca4ea..242614152c 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -540,7 +540,7 @@ static const MemoryRegionOps fw_cfg_data_mem_ops = {
>      .endianness = DEVICE_BIG_ENDIAN,
>      .valid = {
>          .min_access_size = 1,
> -        .max_access_size = 1,
> +        .max_access_size = 8,
>          .accepts = fw_cfg_data_mem_valid,
>      },
>  };
> 

This patch conflicts with (adjacent) commits

- cfaadf0e89e7 ("fw_cfg_mem: introduce the "data_width" property",
2014-12-22) and

- 6c87e3d5967a ("fw_cfg_mem: expose the "data_width" property with
fw_cfg_init_mem_wide()", 2014-12-22)

Your board code is supposed to call the fw_cfg_init_mem_wide() function,
for setting the maximum access width.

In fact, I see a call to fw_cfg_init_mem_wide() in
"hw/mips/loongson3_virt.c" already, from commit c76b409fef19 ("hw/mips:
Add Loongson-3 machine support", 2021-01-04). (I'm only highlighting
this board because your email address is from domain "loongson.cn".)

What is the actual problem you're trying to solve?

Thanks
Laszlo