Re: [PATCH v2] drm/i915: Always program CSR if CSR is uninitialized

From: Animesh Manna <animesh.manna@intel.com>
To: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>,
	intel-gfx@lists.freedesktop.org
Cc: rodrigo.vivi@intel.com
Subject: Re: [PATCH v2] drm/i915: Always program CSR if CSR is uninitialized
Date: Sat, 24 Oct 2015 11:03:05 +0530	[thread overview]
Message-ID: <562B1811.1060000@intel.com> (raw)
In-Reply-To: <1445593310-26596-1-git-send-email-patrik.jakobsson@linux.intel.com>

On 10/23/2015 3:11 PM, Patrik Jakobsson wrote:
> The current CSR loading code depends on the CSR program memory to be
> cleared after boot. This is unfortunately not true on all hardware.
> Instead make use of the FW_UNINITIALIZED state in init and check for
> FW_LOADED to prevent init path from skipping the actual programming.
>
> v2: Move initialization of state to after HAS_CSR() check
>
> Signed-off-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
> Tested-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>   drivers/gpu/drm/i915/intel_csr.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
> index 9e530a7..e74c09e 100644
> --- a/drivers/gpu/drm/i915/intel_csr.c
> +++ b/drivers/gpu/drm/i915/intel_csr.c
> @@ -271,7 +271,7 @@ void intel_csr_load_program(struct drm_device *dev)
>   	 * Unfortunately the ACPI subsystem doesn't yet give us a way to
>   	 * differentiate this, hence figure it out with this hack.
>   	 */
> -	if (I915_READ(CSR_PROGRAM(0)))
> +	if (I915_READ(CSR_PROGRAM(0)) && dev_priv->csr.state == FW_LOADED).state

As I will be removing csr.state in dmc-redesign patch series my suggestion would be to
compare register read with first element of payload like below:

if (I915_READ(CSR_PROGRAM(0)) == dmc_payload[0]) and then skip the f/w loading part.

-Animesh

>   		return;
>   
>   	mutex_lock(&dev_priv->csr_lock);
> @@ -428,6 +428,8 @@ void intel_csr_ucode_init(struct drm_device *dev)
>   	if (!HAS_CSR(dev))
>   		return;
>   
> +	intel_csr_load_status_set(dev_priv, FW_UNINITIALIZED);
> +
>   	if (IS_SKYLAKE(dev))
>   		csr->fw_path = I915_CSR_SKL;
>   	else if (IS_BROXTON(dev_priv))

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