[Intel-gfx] [PATCH] drm/i915: Acquire dpio_lock for VLV sideband programming in DP/HDMI
Daniel Vetter
daniel at ffwll.ch
Fri Jul 26 18:46:43 CEST 2013
On Fri, Jul 26, 2013 at 6:17 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> Otherwise we get flooded by the kernel warning us that we are doing
> long sequences of IO without serialisation. For example,
>
> WARNING: CPU: 0 PID: 11136 at drivers/gpu/drm/i915/intel_sideband.c:40 vlv_sideband_rw+0x48/0x1ef()
> Modules linked in:
> CPU: 0 PID: 11136 Comm: kworker/u2:0 Tainted: G W 3.11.0-rc2+ #4
> Call Trace:
> [<c2028564>] ? warn_slowpath_common+0x63/0x78
> [<c227ad43>] ? vlv_sideband_rw+0x48/0x1ef
> [<c20285dd>] ? warn_slowpath_null+0xf/0x13
> [<c227ad43>] ? vlv_sideband_rw+0x48/0x1ef
> [<c227b060>] ? vlv_dpio_write+0x1c/0x21
> [<c2262b3b>] ? intel_dp_set_signal_levels+0x24a/0x385
> [<c2264909>] ? intel_dp_complete_link_train+0x25/0x1d1
> [<c2264c55>] ? intel_dp_check_link_status+0xf7/0x106
> [<c2238ced>] ? i915_hotplug_work_func+0x17b/0x221
> [<c203a204>] ? process_one_work+0x12e/0x210
> [<c203a5e4>] ? worker_thread+0x116/0x1ad
> [<c203a4ce>] ? rescuer_thread+0x1cb/0x1cb
> [<c203d8f5>] ? kthread+0x67/0x6c
> [<c2457ebb>] ? ret_from_kernel_thread+0x1b/0x30
> [<c203d88e>] ? init_completion+0x18/0x18
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
The problem here is that Jesse was lazy and grabs the lock in
vlv_crtc_enable, so I think your code here will deadlock. But I agree
that grabbing the lock where we actually frob the sideband is what we
want ...
-Daniel
> ---
> drivers/gpu/drm/i915/intel_dp.c | 6 ++++++
> drivers/gpu/drm/i915/intel_hdmi.c | 4 ++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 4a7ba5e..2a455b8 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1719,6 +1719,7 @@ static void intel_pre_enable_dp(struct intel_encoder *encoder)
> int pipe = intel_crtc->pipe;
> u32 val;
>
> + mutex_lock(&dev_priv->dpio_lock);
> val = vlv_dpio_read(dev_priv, DPIO_DATA_LANE_A(port));
> val = 0;
> if (pipe)
> @@ -1732,6 +1733,7 @@ static void intel_pre_enable_dp(struct intel_encoder *encoder)
> 0x00760018);
> vlv_dpio_write(dev_priv, DPIO_PCS_CLOCKBUF8(port),
> 0x00400888);
> + mutex_unlock(&dev_priv->dpio_lock);
> }
> }
>
> @@ -1746,6 +1748,7 @@ static void intel_dp_pre_pll_enable(struct intel_encoder *encoder)
> return;
>
> /* Program Tx lane resets to default */
> + mutex_lock(&dev_priv->dpio_lock);
> vlv_dpio_write(dev_priv, DPIO_PCS_TX(port),
> DPIO_PCS_TX_LANE2_RESET |
> DPIO_PCS_TX_LANE1_RESET);
> @@ -1759,6 +1762,7 @@ static void intel_dp_pre_pll_enable(struct intel_encoder *encoder)
> vlv_dpio_write(dev_priv, DPIO_PCS_STAGGER1(port), 0x00750f00);
> vlv_dpio_write(dev_priv, DPIO_TX_CTL(port), 0x00001500);
> vlv_dpio_write(dev_priv, DPIO_TX_LANE(port), 0x40400000);
> + mutex_unlock(&dev_priv->dpio_lock);
> }
>
> /*
> @@ -1970,6 +1974,7 @@ static uint32_t intel_vlv_signal_levels(struct intel_dp *intel_dp)
> return 0;
> }
>
> + mutex_lock(&dev_priv->dpio_lock);
> vlv_dpio_write(dev_priv, DPIO_TX_OCALINIT(port), 0x00000000);
> vlv_dpio_write(dev_priv, DPIO_TX_SWING_CTL4(port), demph_reg_value);
> vlv_dpio_write(dev_priv, DPIO_TX_SWING_CTL2(port),
> @@ -1978,6 +1983,7 @@ static uint32_t intel_vlv_signal_levels(struct intel_dp *intel_dp)
> vlv_dpio_write(dev_priv, DPIO_PCS_STAGGER0(port), 0x00030000);
> vlv_dpio_write(dev_priv, DPIO_PCS_CTL_OVER1(port), preemph_reg_value);
> vlv_dpio_write(dev_priv, DPIO_TX_OCALINIT(port), 0x80000000);
> + mutex_unlock(&dev_priv->dpio_lock);
>
> return 0;
> }
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 044d11d..5fa3035 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1033,6 +1033,7 @@ static void intel_hdmi_pre_enable(struct intel_encoder *encoder)
> return;
>
> /* Enable clock channels for this port */
> + mutex_lock(&dev_priv->dpio_lock);
> val = vlv_dpio_read(dev_priv, DPIO_DATA_LANE_A(port));
> val = 0;
> if (pipe)
> @@ -1063,6 +1064,7 @@ static void intel_hdmi_pre_enable(struct intel_encoder *encoder)
> 0x00760018);
> vlv_dpio_write(dev_priv, DPIO_PCS_CLOCKBUF8(port),
> 0x00400888);
> + mutex_unlock(&dev_priv->dpio_lock);
> }
>
> static void intel_hdmi_pre_pll_enable(struct intel_encoder *encoder)
> @@ -1076,6 +1078,7 @@ static void intel_hdmi_pre_pll_enable(struct intel_encoder *encoder)
> return;
>
> /* Program Tx lane resets to default */
> + mutex_lock(&dev_priv->dpio_lock);
> vlv_dpio_write(dev_priv, DPIO_PCS_TX(port),
> DPIO_PCS_TX_LANE2_RESET |
> DPIO_PCS_TX_LANE1_RESET);
> @@ -1094,6 +1097,7 @@ static void intel_hdmi_pre_pll_enable(struct intel_encoder *encoder)
> 0x00002000);
> vlv_dpio_write(dev_priv, DPIO_TX_OCALINIT(port),
> DPIO_TX_OCALINIT_EN);
> + mutex_lock(&dev_priv->dpio_lock);
> }
>
> static void intel_hdmi_post_disable(struct intel_encoder *encoder)
> --
> 1.8.3.2
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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