On Tue, Apr 04, 2017 at 07:36:01PM -0700, Stefan Agner wrote: > On 2017-04-04 19:15, Fabio Estevam wrote: > > On Sun, Apr 2, 2017 at 2:02 PM, Fabio Estevam <festevam@xxxxxxxxx> wrote: > >> On Sat, Apr 1, 2017 at 1:15 AM, Stefan Agner <stefan@xxxxxxxx> wrote: > >> > >>> IMX7D_IPG_ROOT_CLK is currently not a valid clock in upstream... So we > >>> would have to add it to the clock driver first. > >>> > >>> I guess we could/should add it anyway at one point? But probably also as > >>> init on, just to make sure Linux does not disable it since it is > >>> currently used by several IPs implicitly. > >> > >> Yes, I made a previous attempt do add IMX7D_IPG_ROOT_CLK and it did > >> not work as I did not put it in the init_on clock list. > >> > >> Will submit a new patch adding it to init_on, thanks. > > > > I thought that adding IMX7D_IPG_ROOT_CLK would do the trick, but the > > patch below also causes the kernel to not boot: > > > > --- a/drivers/clk/imx/clk-imx7d.c > > +++ b/drivers/clk/imx/clk-imx7d.c > > @@ -386,7 +386,7 @@ static int const clks_init_on[] __initconst = { > > IMX7D_PLL_SYS_MAIN_480M_CLK, IMX7D_NAND_USDHC_BUS_ROOT_CLK, > > IMX7D_DRAM_PHYM_ROOT_CLK, IMX7D_DRAM_ROOT_CLK, > > IMX7D_DRAM_PHYM_ALT_ROOT_CLK, IMX7D_DRAM_ALT_ROOT_CLK, > > - IMX7D_AHB_CHANNEL_ROOT_CLK, > > + IMX7D_AHB_CHANNEL_ROOT_CLK, IMX7D_IPG_ROOT_CLK, > > }; > > > > static struct clk_onecell_data clk_data; > > @@ -788,7 +788,7 @@ static void __init imx7d_clocks_init(struct > > device_node *ccm_node) > > clks[IMX7D_WRCLK_ROOT_DIV] = > > imx_clk_divider2("wrclk_post_div", "wrclk_pre_div", base + 0xbd00, 0, > > 6); > > clks[IMX7D_CLKO1_ROOT_DIV] = > > imx_clk_divider2("clko1_post_div", "clko1_pre_div", base + 0xbd80, 0, > > 6); > > clks[IMX7D_CLKO2_ROOT_DIV] = > > imx_clk_divider2("clko2_post_div", "clko2_pre_div", base + 0xbe00, 0, > > 6); > > - > > + clks[IMX7D_IPG_ROOT_CLK] = imx_clk_divider2("ipg_root_clk", > > "ahb_root_clk", base + 0x9080, 0, 2); > > clks[IMX7D_ARM_A7_ROOT_CLK] = imx_clk_gate4("arm_a7_root_clk", > > "arm_a7_div", base + 0x4000, 0); > > clks[IMX7D_ARM_M4_ROOT_CLK] = imx_clk_gate4("arm_m4_root_clk", > > "arm_m4_div", base + 0x4010, 0); > > clks[IMX7D_ARM_M0_ROOT_CLK] = imx_clk_gate4("arm_m0_root_clk", > > "arm_m0_div", base + 0x4020, 0); > > Hm, imx_clk_divider2 sets CLK_SET_RATE_PARENT, maybe that influences the > parent? > > I guess we actually don't want the clock framework to change that clock > rate, not sure whether we can freeze it or similar. > This is caused by ahb_root_clk gets disabled accidently and system hangs. Because this patch defines ipg_root_clk earlier before its parent (ahb_root_clk) got registered, then it will be marked as a orphan clk temporarily. Until the parent ahb_root_clk got registered, the clk core will reparent it to the newly found parent. (see __clk_core_init() function). Due to CLK_SET_RATE_PARENT flag, the ahb clk will be enabled during set_parent operation and then disabled after that. Then system hang cause we still get no chance to run init_on clks. I just send out a proper fix patch with correct register sequence. Probably we can switch all imx clk driver to CLK_IS_CRITICAL for critical clocks in the future, but that's another thing to do later. Stefan, I think you can just resend your series based on my patches. Regards Dong Aisheng > -- > Stefan -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html