On Thu, Apr 3, 2025 at 2:39 AM Miquel Raynal <[email protected]> wrote: > > Reparenting a clock C with a new parent P means that C will only > continue clocking if P is already clocking when the mux is updated. In > case the parent is currently disabled, failures (stalls) are likely to > happen.
Marek made some changes to the clock registration to address some parent-child relationships. Do you know if this patch is still needed? adam > > This is exactly what happens on i.MX8 when enabling the video > pipeline. We tell LCDIF clocks to use the VIDEO PLL as input, while the > VIDEO PLL is currently off. This all happens as part of the > assigned-clocks handling procedure, where the reparenting happens before > the enable() calls. Enabling the parents as part of the reparenting > procedure seems sane and also matches the logic applied in other parts > of the CCM. > > Signed-off-by: Miquel Raynal <[email protected]> > --- > drivers/clk/clk-uclass.c | 21 +++++++++++++++++---- > 1 file changed, 17 insertions(+), 4 deletions(-) > > diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c > index > 90b70529a478d11d907cbd6b64d680d0c1db4d5c..4b3d812f9c6539a6b769990e3e11f14f49abb2a9 > 100644 > --- a/drivers/clk/clk-uclass.c > +++ b/drivers/clk/clk-uclass.c > @@ -623,14 +623,27 @@ int clk_set_parent(struct clk *clk, struct clk *parent) > if (!ops->set_parent) > return -ENOSYS; > > - ret = ops->set_parent(clk, parent); > - if (ret) > + ret = clk_enable(parent); > + if (ret) { > + printf("Cannot enable parent %s\n", parent->dev->name); > return ret; > + } > > - if (CONFIG_IS_ENABLED(CLK_CCF)) > + ret = ops->set_parent(clk, parent); > + if (ret) { > + clk_disable(parent); > + return ret; > + } > + > + if (CONFIG_IS_ENABLED(CLK_CCF)) { > ret = device_reparent(clk->dev, parent->dev); > + if (ret) { > + clk_disable(parent); > + return ret; > + } > + } > > - return ret; > + return 0; > } > > int clk_enable(struct clk *clk) > > -- > 2.48.1 >
