topic Re: About imx8mp clock documentation in i.MX Processors

About imx8mp clock documentation

Chun1 — Mon, 29 Mar 2021 08:52:15 GMT

When I write the clock of imx8mp, I found that there is no IPG_AUDIO_CLK_ROOT register in the document, but I can see that its register is 0x9180 in the Linux code. In addition, the same case for USB_CORE_CLK_REF(0xb100) and CLK_USB_PHY_REF(0xb180). The document I use is iMX_8M_Plus_RM_RevD.pdf, Is the document missing or is there any updated document? thank you.

Re: About imx8mp clock documentation

joanxie — Wed, 31 Mar 2021 07:17:49 GMT

is this the same questions as your another two clock case? we don't have special clock document for imx8mp, what linux code do you mean? clk-i.mx8mp.c? I didn't find IPG_AUDIO_CLK_ROOT as you mentions, give me the detailed linxu code

Re: About imx8mp clock documentation

Chun1 — Wed, 31 Mar 2021 12:07:43 GMT

It's not the same. This is imx8mp clock, not HDMI. the same branch with the two clock case, but the c file is the "drivers/clk/imx/clk-imx8mp.c", below is the code snippet of the IMX8MP_CLK_IPG_AUDIO_ROOT.

/* IPG */ clks[IMX8MP_CLK_IPG_ROOT] = imx_clk_divider2("ipg_root", "ahb_root", base + 0x9080, 0, 1); clks[IMX8MP_CLK_IPG_AUDIO_ROOT] = imx_clk_divider2("ipg_audio_root", "audio_ahb", base + 0x9180, 0, 1);

the offset 0x9180 can't be found in datasheet,

Re: About imx8mp clock documentation

joanxie — Thu, 01 Apr 2021 09:46:19 GMT

AUDIO_AHB_CLK_ROOT belongs to AHB clock, you can find:

/* AHB */
	clks[IMX8MP_CLK_AHB] = imx8m_clk_composite_critical("ahb_root", imx8mp_ahb_sels, base + 0x9000);
	clks[IMX8MP_CLK_AUDIO_AHB] = imx8m_clk_composite("audio_ahb", imx8mp_audio_ahb_sels, base + 0x9100);
	clks[IMX8MP_CLK_MIPI_DSI_ESC_RX] = imx8m_clk_composite("mipi_dsi_esc_rx", imx8mp_mipi_dsi_esc_rx_sels, base + 0x9200);
	clks[IMX8MP_CLK_MEDIA_DISP2_PIX] = imx8m_clk_composite("media_disp2_pix", imx8mp_media_disp2_pix_sels, base + 0x9300);

it seems the table in the RM missed the another audio IPG clock, you can just refer to the source code, maybe the document team will add this in the official released version

Re: About imx8mp clock documentation

Chun1 — Thu, 01 Apr 2021 09:51:58 GMT

This clock(AUDIO_AHB_CLK_ROOT ) is not the only one lost in RM, such as HDMI_REF_24M_CLK_ROOT and so on.

So these missing nodes, I can also directly refer to the source code, right?

Re: About imx8mp clock documentation

joanxie — Thu, 01 Apr 2021 10:03:45 GMT

yes you can refer to the source code if you couldn't find them in the reference manual

Re: About imx8mp clock documentation

Chun1 — Thu, 01 Apr 2021 10:06:53 GMT

OK, thank you.