Re: [PATCH v2] platform/x86/amd/pmc: Detect when STB is not available

[Shyam Sundar S K <Shyam-sundar.S-k@amd.com>]

On 10/27/2024 08:04, Corey Hickey wrote:
> From: Corey Hickey <bugfood-c@fatooh.org>
> 
> Loading the amd_pmc module as:
> 
>     amd_pmc enable_stb=1
> 
> ...can result in the following messages in the kernel ring buffer:
> 
>     amd_pmc AMDI0009:00: SMU cmd failed. err: 0xff
>     ioremap on RAM at 0x0000000000000000 - 0x0000000000ffffff
>     WARNING: CPU: 10 PID: 2151 at arch/x86/mm/ioremap.c:217 __ioremap_caller+0x2cd/0x340
> 
> Additional debug shows that this happens when the calls to obtain
> S2D_PHYS_ADDR_LOW and S2D_PHYS_ADDR_HIGH return 0.
> 
> According to Shyam Sundar S K <Shyam-sundar.S-k@amd.com>, this condition
> indicates that the STB is not available.

No need to put my name in the commit message.

You may simply the commit message to something like this:

Further debugging reveals that this occurs when the requests for
S2D_PHYS_ADDR_LOW and S2D_PHYS_ADDR_HIGH return a value of 0,
indicating that the STB is inaccessible. To prevent the ioremap
warning and provide clarity to the user, handle the invalid address
and display an error message.

With this addressed

Acked-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>

Thanks,
Shyam

> 
> In order to avoid the ioremap warning, and to help the user understand
> the situation, catch the invalid address and print an error.
> 
> Link: https://lore.kernel.org/platform-driver-x86/c588ff5d-3e04-4549-9a86-284b9b4419ba@amd.com
> Fixes: 3d7d407dfb05 ("platform/x86: amd-pmc: Add support for AMD Spill to DRAM STB feature")
> Signed-off-by: Corey Hickey <bugfood-c@fatooh.org>
> ---
>  drivers/platform/x86/amd/pmc/pmc.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/platform/x86/amd/pmc/pmc.c b/drivers/platform/x86/amd/pmc/pmc.c
> index bbb8edb62e00..5669f94c3d06 100644
> --- a/drivers/platform/x86/amd/pmc/pmc.c
> +++ b/drivers/platform/x86/amd/pmc/pmc.c
> @@ -998,6 +998,11 @@ static int amd_pmc_s2d_init(struct amd_pmc_dev *dev)
>  	amd_pmc_send_cmd(dev, S2D_PHYS_ADDR_LOW, &phys_addr_low, dev->s2d_msg_id, true);
>  	amd_pmc_send_cmd(dev, S2D_PHYS_ADDR_HIGH, &phys_addr_hi, dev->s2d_msg_id, true);
>  
> +	if (!phys_addr_hi && !phys_addr_low) {
> +		dev_err(dev->dev, "STB is not enabled on the system; disable enable_stb or contact system vendor\n");
> +		return -EINVAL;
> +	}
> +
>  	stb_phys_addr = ((u64)phys_addr_hi << 32 | phys_addr_low);
>  
>  	/* Clear msg_port for other SMU operation */