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

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

[Xiaojuan Yang]

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,
     },
 };
-- 
2.27.0

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

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

[yangxiaojuan]

Hi,Laszlo

Thanks for your kindly reply.This is my first time to submit
code to the community. I spent some time learning how to configure
the email and reply.

Yes you are right, fw_cfg_init_mem_wide can solve my problem.
I just want to access 8 bytes width.I did not look at the code
carefully.I am so sorry. My patch can be abandoned.

I am from loongson. We want to add a new board support to
the community.Later we will submit more code.

thanks
Xiaojuan Yang


On 5/18/21 11:49 PM, Laszlo Ersek wrote:
> 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
>