[PATCH 2/2] drm/etnaviv: fix power register offset on GC300

[Christian Gmeiner]

Hi

>
> Older GC300 revisions have their power registers at an offset of 0x200
> rather than 0x100.
>
> Signed-off-by: Doug Brown <doug at schmorgal.com>
> ---
>  drivers/gpu/drm/etnaviv/etnaviv_gpu.h | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
> index 85eddd492774..b375612df862 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
> @@ -10,6 +10,8 @@
>  #include "etnaviv_gem.h"
>  #include "etnaviv_mmu.h"
>  #include "etnaviv_drv.h"
> +#include "common.xml.h"
> +#include "state_hi.xml.h"
>
>  struct etnaviv_gem_submit;
>  struct etnaviv_vram_mapping;
> @@ -149,14 +151,24 @@ struct etnaviv_gpu {
>         unsigned long base_rate_shader;
>  };
>
> +static inline u32 gpu_fix_reg_address(struct etnaviv_gpu *gpu, u32 reg)
> +{
> +       /* Power registers in GC300 < 2.0 are offset by 0x100 */
> +       if (reg >= VIVS_PM_POWER_CONTROLS && reg <= VIVS_PM_PULSE_EATER &&
> +           gpu->identity.model == chipModel_GC300 &&
> +           gpu->identity.revision < 0x2000)
> +               reg += 0x100;
> +       return reg;
> +}
> +
>  static inline void gpu_write(struct etnaviv_gpu *gpu, u32 reg, u32 data)
>  {
> -       writel(data, gpu->mmio + reg);
> +       writel(data, gpu->mmio + gpu_fix_reg_address(gpu, reg));
>  }
>
>  static inline u32 gpu_read(struct etnaviv_gpu *gpu, u32 reg)
>  {
> -       return readl(gpu->mmio + reg);
> +       return readl(gpu->mmio + gpu_fix_reg_address(gpu, reg));
>  }
>

I had a quick look at what vivantes kernel driver did. It uses a per
gpu instance variable powerBaseAddress
that gets set accordingly. I am not sure if I really like the
gpu_fix_reg_address(..) idea, as it gets called on every
register read and write. For me I see two other possible solutions:

1) Add two seperate helpers ala gpu_read_power() and gpu_write_power()
where we do the if beast.
2) Add a power register offset variable to etnaviv_gpu and explicitly
use it on for reads and writes - like the Vivante driver does.

But that's just my personal opinion. Can't wait to hear what Lucas thinks.

-- 
greets
--
Christian Gmeiner, MSc

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