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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+linux-amlogic=archiver.kernel.org@lists.infradead.org Hi Jerome, Thank you for reviewing, and apologies for my late response due to a holiday. > On Thu 13 Feb 2025 at 23:17, Martijn van Deventer > wrote: > > > When booting SM1 or G12A boards without a dislay attached to HDMI, > > the kernel shows the following warning: > > > > [CRTC:46:meson_crtc] vblank wait timed out > > WARNING: CPU: 2 PID: 265 at drivers/gpu/drm/drm_atomic_helper.c:1682 > drm_atomic_helper_wait_for_vblanks.part.0+0x240/0x264 > > CPU: 2 UID: 0 PID: 265 Comm: setfont Tainted: G C > > Tainted: [C]=CRAP > > pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > > pc : drm_atomic_helper_wait_for_vblanks.part.0+0x240/0x264 > > lr : drm_atomic_helper_wait_for_vblanks.part.0+0x240/0x264 > > Call trace: > > drm_atomic_helper_wait_for_vblanks.part.0+0x240/0x264 > > drm_atomic_helper_commit_tail_rpm+0x84/0xa0 > > commit_tail+0xa4/0x18c > > drm_atomic_helper_commit+0x164/0x178 > > drm_atomic_commit+0xb4/0xec > > drm_client_modeset_commit_atomic+0x210/0x270 > > drm_client_modeset_commit_locked+0x5c/0x188 > > drm_fb_helper_pan_display+0xb8/0x1d4 > > fb_pan_display+0x7c/0x120 > > bit_update_start+0x20/0x48 > > fbcon_switch+0x418/0x54c > > el0t_64_sync+0x194/0x198 > > > > This happens when the kernel disables the unused clocks. > > Sometimes this causes the boot to hang. > > > > By (re)adding the flag CLK_IGNORE_UNUSED to the VCLK2 clocks, these > > clocks will not be disabled. > > > > This partially reverts commit b70cb1a21a54 ("clk: meson: g12a: > > make VCLK2 and ENCL clock path configurable by CCF"). > > It looks like DRM needs those clock enabled regardless of connection > status on HDMI. Even with this change applied, you would get the same > problem again if the bootloader does not take of turning the clock on, > which is not a given. > > CLK_IGNORE_UNUSED gives not guarantee a clock will be enabled or stay > enabled at any point. > > A proper fix to this issue should be done in DRM, IMO. I know and I totally agree. Unfortunately, I don't have access to any vendor documentation, nor do I have any real knowledge about the DRM/HDMI subsystem to fix that. And I guess if it were as easy as adding a clock to the DT and calling clk_prepare_enable on it in the probe function, Neil would have done that already. So, all I can do, for now, is revert to the previous situation when it did work for (probably) most boards. > > > > Fixes: b70cb1a21a54 ("clk: meson: g12a: make VCLK2 and ENCL clock path > configurable by CCF"). > > Signed-off-by: Martijn van Deventer > > --- > > drivers/clk/meson/g12a.c | 12 ++++++------ > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c > > index cfffd434e998..1651898658f5 100644 > > --- a/drivers/clk/meson/g12a.c > > +++ b/drivers/clk/meson/g12a.c > > @@ -3234,7 +3234,7 @@ static struct clk_regmap g12a_vclk2_div = { > > &g12a_vclk2_input.hw > > }, > > .num_parents = 1, > > - .flags = CLK_SET_RATE_GATE, > > + .flags = CLK_SET_RATE_GATE | CLK_IGNORE_UNUSED, > > }, > > }; > > > > @@ -3270,7 +3270,7 @@ static struct clk_regmap g12a_vclk2 = { > > .ops = &meson_vclk_gate_ops, > > .parent_hws = (const struct clk_hw *[]) { &g12a_vclk2_div.hw > }, > > .num_parents = 1, > > - .flags = CLK_SET_RATE_PARENT, > > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > > }, > > }; > > > > @@ -3354,7 +3354,7 @@ static struct clk_regmap g12a_vclk2_div1 = { > > .ops = &clk_regmap_gate_ops, > > .parent_hws = (const struct clk_hw *[]) { &g12a_vclk2.hw }, > > .num_parents = 1, > > - .flags = CLK_SET_RATE_PARENT, > > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > > }, > > }; > > > > @@ -3368,7 +3368,7 @@ static struct clk_regmap g12a_vclk2_div2_en = { > > .ops = &clk_regmap_gate_ops, > > .parent_hws = (const struct clk_hw *[]) { &g12a_vclk2.hw }, > > .num_parents = 1, > > - .flags = CLK_SET_RATE_PARENT, > > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > > }, > > }; > > > > @@ -3382,7 +3382,7 @@ static struct clk_regmap g12a_vclk2_div4_en = { > > .ops = &clk_regmap_gate_ops, > > .parent_hws = (const struct clk_hw *[]) { &g12a_vclk2.hw }, > > .num_parents = 1, > > - .flags = CLK_SET_RATE_PARENT, > > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > > }, > > }; > > > > @@ -3396,7 +3396,7 @@ static struct clk_regmap g12a_vclk2_div6_en = { > > .ops = &clk_regmap_gate_ops, > > .parent_hws = (const struct clk_hw *[]) { &g12a_vclk2.hw }, > > .num_parents = 1, > > - .flags = CLK_SET_RATE_PARENT, > > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > > }, > > }; > -- Martijn _______________________________________________ linux-amlogic mailing list linux-amlogic@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-amlogic