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 ---
Notes: Changes since v8: - new patch
drivers/clk/rockchip/clk-rk3568.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/clk/rockchip/clk-rk3568.c b/drivers/clk/rockchip/clk-rk3568.c index 63dfbeeeb06d9..62694d95173ab 100644 --- a/drivers/clk/rockchip/clk-rk3568.c +++ b/drivers/clk/rockchip/clk-rk3568.c @@ -1591,6 +1591,7 @@ static const char *const rk3568_cru_critical_clocks[] __initconst = { "hclk_php", "pclk_php", "hclk_usb", + "hclk_vo", };
static const char *const rk3568_pmucru_critical_clocks[] __initconst = {