On 12/22/25 22:32, Arnd Bergmann wrote:
> On Sat, Dec 20, 2025, at 17:33, Han Gao wrote:
>> diff --git a/drivers/gpu/drm/radeon/radeon_drv.c
>> b/drivers/gpu/drm/radeon/radeon_drv.c
>> index 87fd6255c114..53af28494c03 100644
>> --- a/drivers/gpu/drm/radeon/radeon_drv.c
>> +++ b/drivers/gpu/drm/radeon/radeon_drv.c
>> @@ -249,6 +249,10 @@ int radeon_cik_support = -1;
>> MODULE_PARM_DESC(cik_support, "CIK support (1 = enabled, 0 = disabled,
>> -1 = default)");
>> module_param_named(cik_support, radeon_cik_support, int, 0444);
>>
>> +int radeon_msi64;
>> +MODULE_PARM_DESC(msi64, "MSI64 support (1 = enabled, 0 = disabled)");
>> +module_param_named(msi64, radeon_msi64, int, 0444);
>> +
>
> As with the hda-intel patch, this should not be a module argument,
> but we should have the kernel figure out what to do itself.
Yeah, completely agree. This is basically just a workaround (and a bit ugly
one).
>> diff --git a/drivers/gpu/drm/radeon/radeon_irq_kms.c
>> b/drivers/gpu/drm/radeon/radeon_irq_kms.c
>> index 9961251b44ba..62eb5a6968ff 100644
>> --- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
>> +++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c
>> @@ -250,7 +250,7 @@ static bool radeon_msi_ok(struct radeon_device
>> *rdev)
>> * of address for "64-bit" MSIs which breaks on some platforms,
>> notably
>> * IBM POWER servers, so we limit them
>> */
>> - if (rdev->family < CHIP_BONAIRE) {
>> + if (rdev->family < CHIP_BONAIRE && !radeon_msi64) {
>> dev_info(rdev->dev, "radeon: MSI limited to 32-bit\n");
>> rdev->pdev->no_64bit_msi = 1;
>
> According to the comment above it, the device can apparently
> do 40-bit addressing but not use the entire 64-bit space.
>
> I assume the SG2042 chip has the irqchip somewhere above the
> 32-bit line but below the 40-bit line, so it ends up working.
>
> I wonder if the msi_verify_entries() function should check
> against dev->coherent_dma_mask instead of checking the
> upper 32 bits for being nonzero, that probably gives you
> the desired behavior.
Again completely agree, that sounds like a plan to me.
IIRC the modified code here is basically just a workaround because the MSI
control dword on older radeon HW was not setup correctly.
Regards,
Christian.
>
> Arnd
