Re: Question regarding clocks in the DW-HDMI DT bindings

[Philipp Zabel <p.zabel@pengutronix.de>]

Hi Laurent,

Am Donnerstag, den 24.11.2016, 23:16 +0200 schrieb Laurent Pinchart:
> Hi Andy,
> 
> As the author of the DW-HDMI DT bindings this question is addressed to you, 
> but information from anyone is more than welcome.
> 
> The DT bindings specify two clocks named "iahb" and "isfr" but don't describe 
> them. While I assume that the "isfr" clock corresponds to the "isfrclk" input 
> signal of the DW HDMI, there is no "iahb" clock described in the IP core 
> datasheet.

The Table 33-1 "HDMI clocks" in the i.MX6DQ reference manual [1] lists
iahbclk (AHB bus clock), icecclk (32 kHz CEC clock), ihclk (module
clock) and isfrclk (27 MHz internal SFR clock).

[1] http://www.nxp.com/assets/documents/data/en/reference-manuals/IMX6DQRM.pdf

> The DW HDMI IP exposes control registers through an APB, not an AHB. There is 
> a bus clock named "iapbclk", is "iahb" just an incorrect name for that clock ?

According to figure 33-3 "HDMI TX Top Level Block Diagram" the control
interface is AMBA AHB on i.MX6. Both iahbclk and ihclk are clocked by
ahb_clk_root on i.MX6.
Register 5 (HDMI_CONFIG1_ID) contains a few bits (confsfrdir, confi2c,
confocp, confapb, confahb) that indicate which control interface is
used.

regards
Philipp

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