Am Donnerstag, den 07.03.2019, 12:56 +0000 schrieb Anson Huang: > Hi, Lucas > > Best Regards! > Anson Huang > > > -----Original Message----- > > > > From: Lucas Stach [mailto:l.st...@pengutronix.de] > > Sent: 2019年3月7日 20:06 > > > > > > To: Anson Huang <anson.hu...@nxp.com>; shawn...@kernel.org; > > > > s.ha...@pengutronix.de; ker...@pengutronix.de; Fabio Estevam > > > > > > > > <fabio.este...@nxp.com>; robh...@kernel.org; > > > > > > > > mark.rutl...@arm.com; > > > > mturque...@baylibre.com; sb...@kernel.org; Abel Vesa > > > > > > <abel.v...@nxp.com>; a...@sigxcpu.org; linux-arm- > > > > ker...@lists.infradead.org; devicet...@vger.kernel.org; linux- > > ker...@vger.kernel.org; linux-...@vger.kernel.org > > > > Cc: dl-linux-imx <linux-...@nxp.com> > > Subject: Re: [PATCH 2/3] clk: imx8mq: add hdmi_phy_27m clock as pll's > > reference clock > > > > Am Donnerstag, den 07.03.2019, 03:41 +0000 schrieb Anson Huang: > > > There is another 27MHz OSC inside i.MX8MQ's display block and it can > > > be one of reference clocks of all PLLs, add it into clock tree and > > > also add it as PLL's reference clock. > > > > > > > > > Signed-off-by: Anson Huang <anson.hu...@nxp.com> > > > --- > > > drivers/clk/imx/clk-imx8mq.c | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/clk/imx/clk-imx8mq.c > > > b/drivers/clk/imx/clk-imx8mq.c index a9b3888..bb1bf9b 100644 > > > --- a/drivers/clk/imx/clk-imx8mq.c > > > +++ b/drivers/clk/imx/clk-imx8mq.c > > > @@ -26,7 +26,7 @@ static u32 share_count_nand; > > > > > > static struct clk *clks[IMX8MQ_CLK_END]; > > > > > > -static const char * const pll_ref_sels[] = { "osc_25m", "osc_27m", > > > "dummy", "dummy", }; > > > +static const char * const pll_ref_sels[] = { "osc_25m", "osc_27m", > > > +"osc_hdmi_phy_27m", "dummy", }; > > > static const char * const arm_pll_bypass_sels[] = {"arm_pll", > > > "arm_pll_ref_sel", }; > > > static const char * const gpu_pll_bypass_sels[] = {"gpu_pll", > > > "gpu_pll_ref_sel", }; > > > static const char * const vpu_pll_bypass_sels[] = {"vpu_pll", > > > "vpu_pll_ref_sel", }; @@ -281,6 +281,7 @@ static int > > > > imx8mq_clocks_probe(struct platform_device *pdev) > > > > > > clks[IMX8MQ_CLK_32K] = of_clk_get_by_name(np, "ckil"); > > > > > > clks[IMX8MQ_CLK_25M] = of_clk_get_by_name(np, "osc_25m"); > > > > > > clks[IMX8MQ_CLK_27M] = of_clk_get_by_name(np, "osc_27m"); > > > > > > + clks[IMX8MQ_CLK_HDMI_PHY_27M] = of_clk_get_by_name(np, > > > +"osc_hdmi_phy_27m"); > > > > This is not acceptable. This adds a new required clock input, without > > bothering to add the corresponding binding information or thinking about > > backwards compatibility. At this point there are existing DTs out there, > > which > > don't provide this required clock, which will cause a full boot regression. > > This > > can only be an optional clock input at this point. > > What do you think if we don't get such clock from DT? Just register this > fixed clock > in clock driver directly, then there will be no dependency of DT.
I don't think that's a good idea, as there can probably be use-cases where having the XTAL unpopulated is actually a valid system configuration, so not having this clock must be valid for the CCM driver. Regards, Lucas
