Hi Philipp, On Wed, Feb 11, 2015 at 02:00:48PM +0100, Philipp Zabel wrote: > Hi Liu, > > Am Mittwoch, den 11.02.2015, 15:21 +0800 schrieb Liu Ying: > [...] > > Our internal MIPI DSI SoC owner gave me some feedbacks on the clock sources. > > According to him, the Synopsys DesignWare MIPI DSI host controller needs four > > clock sources from an application platform - pclk, refclk, cfg_clk and dpipclk. > > These clocks are mentioned in the "DesignWare Cores MIPI DSI Host Controller > > Databook, 1.01a1.30a.pdf" documentation. > > > > Quote some words from the documentation: > > pclk - APB clock signal. > > refclk - D-PHY reference clock used for Master-side serial clock generation in > > clock multiplying unit(PLL). > > cfg_clk - D-PHY Configuration clock used for the initialization of the PHY. It > > is also used for exiting ULPS state. > > dpipclk - Input Pixel clock signal. > > > > The below table reflects how does i.MX6Q/DL provide the pclk, refclk and cfg_clk > > for the DesignWare MIPI DSI host controller, according to the SoC owner. > > ---------------------------------------------------------------------------- > > | Synopsys | i.MX6Q/DL MIPI DSI | > > | DesignWare |------------------------------------------------------------| > > | documentation | clock | clock root | CCM_CCGR bits | > > |---------------|------------|--------------------|--------------------------| > > | pclk | ips_clk | ipg_clk_root | mipi_core_cfg_clk_enable | > > |---------------|------------|--------------------|--------------------------| > > | refclk | pll_refclk | video_27m_clk_root | mipi_core_cfg_clk_enable | > > |---------------|------------|--------------------|--------------------------| > > | cfg_clk | cfg_clk | video_27m_clk_root | mipi_core_cfg_clk_enable | > > ---------------------------------------------------------------------------- > > > > I think we should add a new clock "IMX6QDL_CLK_MIPI_IPG" as a shared clock gate > > clock. > > That would be necessary if the pclk clock rate mattered or would be set > anywhere. I don't think the pclk clock rate matters a lot. It should be sufficient for the driver only to enable/disable the pclk for registers access, just like the way the pwm-imx driver uses the ipg clock. > > > And, the clock-names property should exactly contain "pclk", "refclk" > > and "cfg_clk", right? > > My personal preference would be to drop the superfluous "clk" prefix if > the resulting clock name is still clearly relatable to the official > name. Existing clock naming for the pclk is a bit mixed - > The "snps,dw-apb-timer" binding uses "pclk", which seems to be quite > common in other places, too. The "snps,dw-apb-uart" bindings use > "apb_pclk". "snps,dw-hdmi-tx" uses "iahb" and "isfr" without the clk > suffix. > How about "pclk", "ref" and "cfg"? Looks good and clear enough. I'd like to use them. Thanks. BTW, regarding the compatible string topic, shall I keep my implementation unchanged and don't append the additional "snps,dw-mipi-dsi" as I shared my concerns about it before? Regards, Liu Ying > > regards > Philipp > -- 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
