Whenever pclk_vo is enabled hclk_vo must be enabled as well. This is
described in the Reference Manual as:
| 2.8.6 NIU Clock gating reliance
|
| A part of niu clocks have a dependence on another niu clock in order to
| sharing the internal bus. When these clocks are in use, another niu
| clock must be opened, and cannot be gated. These clocks and the special
| clock on which they are relied are as following:
|
| Clocks which have dependency The clock which can not be gated
| -----------------------------------------------------------------
| ...
| pclk_vo_niu, hclk_vo_s_niu hclk_vo_niu
| ...
The clock framework doesn't offer a way to enable clock B whenever clock A is
enabled, at least not when B is not an ancestor of A. Workaround this by
marking hclk_vo as critical so it is never disabled. This is suboptimal in
terms of power consumption, but a stop gap solution until the clock framework
has a way to deal with this.
We have this clock tree:
| aclk_vo 2 2 0 300000000 0 0 50000 Y
| aclk_hdcp 0 0 0 300000000 0 0 50000 N
| pclk_vo 2 3 0 75000000 0 0 50000 Y
| pclk_edp_ctrl 0 0 0 75000000 0 0 50000 N
| pclk_dsitx_1 0 0 0 75000000 0 0 50000 N
| pclk_dsitx_0 1 2 0 75000000 0 0 50000 Y
| pclk_hdmi_host 1 2 0 75000000 0 0 50000 Y
| pclk_hdcp 0 0 0 75000000 0 0 50000 N
| hclk_vo 2 5 0 150000000 0 0 50000 Y
| hclk_hdcp 0 0 0 150000000 0 0 50000 N
| hclk_vop 0 2 0 150000000 0 0 50000 N
Without this patch the edp, dsitx, hdmi and hdcp driver would enable their
clocks which then enables pclk_vo, but hclk_vo stays disabled and register
accesses just hang. hclk_vo is enabled by the VOP2 driver, so reproducibility
of this issue depends on the probe order.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Michael Riesch <michael.riesch@wolfvision.net>
Link: https://lore.kernel.org/r/20220422072841.2206452-2-s.hauer@pengutronix.de
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
6931f85c29