On Thu, 23 Feb 2017, Chris Wilson <ch...@chris-wilson.co.uk> wrote:
> After initiating a sideband transaction, we only want to wait for the
> transaction to become idle. If, as we are, we wait for both the busy
> and error flag to clear, if an error is raised we just spin until the
> timeout. Once the hw is idle, we can then check to see if the hw flagged
> an error, and report it distinctly.
>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nik...@intel.com>
Much better indeed.
Reviewed-by: Jani Nikula <jani.nik...@intel.com>
(The pedantic nitpick is that response status is really two bits, and
you could read them both and fail if they're not zero. But meh.)
> ---
> drivers/gpu/drm/i915/intel_sideband.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_sideband.c
> b/drivers/gpu/drm/i915/intel_sideband.c
> index 9f782b5eb6e6..41712ea9f5f8 100644
> --- a/drivers/gpu/drm/i915/intel_sideband.c
> +++ b/drivers/gpu/drm/i915/intel_sideband.c
> @@ -216,6 +216,7 @@ u32 intel_sbi_read(struct drm_i915_private *dev_priv, u16
> reg,
> }
>
> I915_WRITE(SBI_ADDR, (reg << 16));
> + I915_WRITE(SBI_DATA, 0);
>
> if (destination == SBI_ICLK)
> value = SBI_CTL_DEST_ICLK | SBI_CTL_OP_CRRD;
> @@ -225,10 +226,15 @@ u32 intel_sbi_read(struct drm_i915_private *dev_priv,
> u16 reg,
>
> if (intel_wait_for_register(dev_priv,
> SBI_CTL_STAT,
> - SBI_BUSY | SBI_RESPONSE_FAIL,
> + SBI_BUSY,
> 0,
> 100)) {
> - DRM_ERROR("timeout waiting for SBI to complete read
> transaction\n");
> + DRM_ERROR("timeout waiting for SBI to complete read\n");
> + return 0;
> +
> + }
> + if (I915_READ(SBI_CTL_STAT) & SBI_RESPONSE_FAIL) {
> + DRM_ERROR("error during SBI read of reg %x\n", reg);
> return 0;
> }
>
> @@ -260,10 +266,16 @@ void intel_sbi_write(struct drm_i915_private *dev_priv,
> u16 reg, u32 value,
>
> if (intel_wait_for_register(dev_priv,
> SBI_CTL_STAT,
> - SBI_BUSY | SBI_RESPONSE_FAIL,
> + SBI_BUSY,
> 0,
> 100)) {
> - DRM_ERROR("timeout waiting for SBI to complete write
> transaction\n");
> + DRM_ERROR("timeout waiting for SBI to complete write\n");
> + return;
> + }
> +
> + if (I915_READ(SBI_CTL_STAT) & SBI_RESPONSE_FAIL) {
> + DRM_ERROR("error during SBI write of %x to reg %x\n",
> + value, reg);
> return;
> }
> }
--
Jani Nikula, Intel Open Source Technology Center
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