Re: [PATCH 08/16] gpu: nova-core: wait for GFW_BOOT completion

["Alexandre Courbot" <acourbot@nvidia.com>]

On Tue Apr 22, 2025 at 8:36 PM JST, Danilo Krummrich wrote:
> On Sun, Apr 20, 2025 at 09:19:40PM +0900, Alexandre Courbot wrote:
>> Upon reset, the GPU executes the GFW_BOOT firmware in order to
>> initialize its base parameters such as clocks. The driver must ensure
>> that this step is completed before using the hardware.
>> 
>> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
>> ---
>>  drivers/gpu/nova-core/devinit.rs   | 40 ++++++++++++++++++++++++++++++++++++++
>>  drivers/gpu/nova-core/driver.rs    |  2 +-
>>  drivers/gpu/nova-core/gpu.rs       |  5 +++++
>>  drivers/gpu/nova-core/nova_core.rs |  1 +
>>  drivers/gpu/nova-core/regs.rs      | 11 +++++++++++
>>  5 files changed, 58 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/nova-core/devinit.rs b/drivers/gpu/nova-core/devinit.rs
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..ee5685aff845aa97d6b0fbe9528df9a7ba274b2c
>> --- /dev/null
>> +++ b/drivers/gpu/nova-core/devinit.rs
>> @@ -0,0 +1,40 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +//! Methods for device initialization.
>> +
>> +use kernel::bindings;
>> +use kernel::devres::Devres;
>> +use kernel::prelude::*;
>> +
>> +use crate::driver::Bar0;
>> +use crate::regs;
>> +
>> +/// Wait for devinit FW completion.
>> +///
>> +/// Upon reset, the GPU runs some firmware code to setup its core parameters. Most of the GPU is
>> +/// considered unusable until this step is completed, so it must be waited on very early during
>> +/// driver initialization.
>> +pub(crate) fn wait_gfw_boot_completion(bar: &Devres<Bar0>) -> Result<()> {
>> +    let mut timeout = 2000;
>> +
>> +    loop {
>> +        let gfw_booted = with_bar!(
>> +            bar,
>> +            |b| regs::Pgc6AonSecureScratchGroup05PrivLevelMask::read(b)
>> +                .read_protection_level0_enabled()
>> +                && (regs::Pgc6AonSecureScratchGroup05::read(b).value() & 0xff) == 0xff
>> +        )?;
>> +
>> +        if gfw_booted {
>> +            return Ok(());
>> +        }
>> +
>> +        if timeout == 0 {
>> +            return Err(ETIMEDOUT);
>> +        }
>> +        timeout -= 1;
>> +
>> +        // SAFETY: msleep should be safe to call with any parameter.
>> +        unsafe { bindings::msleep(2) };
>
> I assume this goes away with [1]? Can we please add a corresponding TODO? Also,
> do you mind preparing the follow-up patches for cases like this (there's also
> the transmute one), such that we can apply them, once the dependencies did land
> and such that we can verify that they suit our needs?
>
> [1] https://lore.kernel.org/lkml/20250220070611.214262-8-fujita.tomonori@gmail.com/

Good idea. Added the TODO item with a link to the patch.

>
>> +    }
>> +}
>> diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
>> index a08fb6599267a960f0e07b6efd0e3b6cdc296aa4..752ba4b0fcfe8d835d366570bb2f807840a196da 100644
>> --- a/drivers/gpu/nova-core/driver.rs
>> +++ b/drivers/gpu/nova-core/driver.rs
>> @@ -10,7 +10,7 @@ pub(crate) struct NovaCore {
>>      pub(crate) gpu: Gpu,
>>  }
>>  
>> -const BAR0_SIZE: usize = 8;
>> +const BAR0_SIZE: usize = 0x1000000;
>>  pub(crate) type Bar0 = pci::Bar<BAR0_SIZE>;
>>  
>>  kernel::pci_device_table!(
>> diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
>> index 866c5992b9eb27735975bb4948e522bc01fadaa2..1f7799692a0ab042f2540e01414f5ca347ae9ecc 100644
>> --- a/drivers/gpu/nova-core/gpu.rs
>> +++ b/drivers/gpu/nova-core/gpu.rs
>> @@ -2,6 +2,7 @@
>>  
>>  use kernel::{device, devres::Devres, error::code::*, pci, prelude::*};
>>  
>> +use crate::devinit;
>>  use crate::driver::Bar0;
>>  use crate::firmware::Firmware;
>>  use crate::regs;
>> @@ -168,6 +169,10 @@ pub(crate) fn new(
>>              spec.revision
>>          );
>>  
>> +        // We must wait for GFW_BOOT completion before doing any significant setup on the GPU.
>> +        devinit::wait_gfw_boot_completion(&bar)
>> +            .inspect_err(|_| pr_err!("GFW boot did not complete"))?;
>> +
>>          Ok(pin_init!(Self { spec, bar, fw }))
>>      }
>>  }
>> diff --git a/drivers/gpu/nova-core/nova_core.rs b/drivers/gpu/nova-core/nova_core.rs
>> index 0eecd612e34efc046dad852e6239de6ffa5fdd62..878161e060f54da7738c656f6098936a62dcaa93 100644
>> --- a/drivers/gpu/nova-core/nova_core.rs
>> +++ b/drivers/gpu/nova-core/nova_core.rs
>> @@ -20,6 +20,7 @@ macro_rules! with_bar {
>>      }
>>  }
>>  
>> +mod devinit;
>>  mod driver;
>>  mod firmware;
>>  mod gpu;
>> diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
>> index e315a3011660df7f18c0a3e0582b5845545b36e2..fd7096f0ddd4af90114dd1119d9715d2cd3aa2ac 100644
>> --- a/drivers/gpu/nova-core/regs.rs
>> +++ b/drivers/gpu/nova-core/regs.rs
>> @@ -13,3 +13,14 @@
>>      7:4     major_rev => as u8, "major revision of the chip";
>>      28:20   chipset => try_into Chipset, "chipset model"
>>  );
>> +
>> +/* GC6 */
>> +
>> +register!(Pgc6AonSecureScratchGroup05PrivLevelMask@0x00118128;
>> +    0:0     read_protection_level0_enabled => as_bit bool
>> +);
>> +
>> +/* TODO: This is an array of registers. */
>> +register!(Pgc6AonSecureScratchGroup05@0x00118234;
>> +    31:0    value => as u32
>> +);
>
> Please also document new register definitions.

Thankfully Joel's documentation patches take care of this!

Cheers,
Alex.