Re: next/master bisection: baseline.dmesg.emerg on meson-gxbb-p200

[Marc Zyngier <maz@kernel.org>]

On 2020-11-19 10:26, Neil Armstrong wrote:
> On 19/11/2020 11:20, Marc Zyngier wrote:
>> On 2020-11-19 08:50, Guillaume Tucker wrote:
>>> Please see the automated bisection report below about some kernel
>>> errors on meson-gxbb-p200.
>>> 
>>> Reports aren't automatically sent to the public while we're
>>> trialing new bisection features on kernelci.org, however this one
>>> looks valid.
>>> 
>>> The bisection started with next-20201118 but the errors are still
>>> present in next-20201119.  Details for this regression:
>>> 
>>>   https://kernelci.org/test/case/id/5fb6196bfd0127fd68d8d902/
>>> 
>>> The first error is:
>>> 
>>>   [   14.757489] Internal error: synchronous external abort: 96000210
>>> [#1] PREEMPT SMP
>> 
>> Looks like yet another clock ordering setup. I guess different Amlogic
>> platforms have slightly different ordering requirements.
>> 
>> Neil, do you have any idea of which platform requires which ordering?
>> The variability in DT and platforms is pretty difficult to follow (and
>> I don't think I have such board around).
> 
> The requirements should be the same, here the init was done before 
> calling
> dw_hdmi_probe to be sure the clocks and internals resets were 
> deasserted.
> But since you boot from u-boot already enabling these, it's already 
> active.
> 
> The solution would be to revert and do some check in 
> meson_dw_hdmi_init() to
> check if already enabled and do nothing.

A better fix seems to be this, which makes it explicit that there is
a dependency between some of the registers accessed from 
meson_dw_hdmi_init()
and the iahb clock.

Guillaume, can you give this a go on your failing box?

Thanks,

         M.

diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c 
b/drivers/gpu/drm/meson/meson_dw_hdmi.c
index 7f8eea494147..52af8ba94311 100644
--- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
+++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
@@ -146,6 +146,7 @@ struct meson_dw_hdmi {
  	struct reset_control *hdmitx_ctrl;
  	struct reset_control *hdmitx_phy;
  	struct clk *hdmi_pclk;
+	struct clk *iahb_clk;
  	struct clk *venci_clk;
  	struct regulator *hdmi_supply;
  	u32 irq_stat;
@@ -1033,6 +1034,13 @@ static int meson_dw_hdmi_bind(struct device *dev, 
struct device *master,
  	}
  	clk_prepare_enable(meson_dw_hdmi->hdmi_pclk);

+	meson_dw_hdmi->iahb_clk = devm_clk_get(dev, "iahb");
+	if (IS_ERR(meson_dw_hdmi->iahb_clk)) {
+		dev_err(dev, "Unable to get iahb clk\n");
+		return PTR_ERR(meson_dw_hdmi->iahb_clk);
+	}
+	clk_prepare_enable(meson_dw_hdmi->iahb_clk);
+
  	meson_dw_hdmi->venci_clk = devm_clk_get(dev, "venci");
  	if (IS_ERR(meson_dw_hdmi->venci_clk)) {
  		dev_err(dev, "Unable to get venci clk\n");
@@ -1071,6 +1079,8 @@ static int meson_dw_hdmi_bind(struct device *dev, 
struct device *master,

  	encoder->possible_crtcs = BIT(0);

+	meson_dw_hdmi_init(meson_dw_hdmi);
+
  	DRM_DEBUG_DRIVER("encoder initialized\n");

  	/* Bridge / Connector */
@@ -1095,8 +1105,6 @@ static int meson_dw_hdmi_bind(struct device *dev, 
struct device *master,
  	if (IS_ERR(meson_dw_hdmi->hdmi))
  		return PTR_ERR(meson_dw_hdmi->hdmi);

-	meson_dw_hdmi_init(meson_dw_hdmi);
-
  	next_bridge = of_drm_find_bridge(pdev->dev.of_node);
  	if (next_bridge)
  		drm_bridge_attach(encoder, next_bridge,


-- 
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