How can we tune or adjust pixel clock for i.MX6 HDMI ?
Tried 2 cases in 1280x1024@60 then 9259 and 9278 pixclock periods worked.
As the driver calculated, pixclock frequency were 108.003MHz and 107.781MHz.
In actual pixclock frequency from i.MX6, 108.3MHz and 107.7MHz.
So there are some offsets between calculated pixclock frequency and actual frequency.
Just questions.
1) Is the frequency offset caused by i.MX6 hardware like PLL or clock controller inside ?
2) Can we tune or adjust the frequency into specific range like 108.003MHz ?
/* 20 1280x1024-60 VESA */
{ NULL, 60, 1280, 1024, 9259, 248, 48, 38, 1, 112, 3,
FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT,
FB_VMODE_NONINTERLACED },
mxc_hdmi mxc_hdmi: Non-CEA mode used in HDMI mxc_hdmi mxc_hdmi: hdmi_av_composer modedb fb_var_to_videomode: ----- var -----
modedb fb_var_to_videomode: pixclock : 9259
modedb fb_var_to_videomode: xres : 1280
modedb fb_var_to_videomode: right_margin : 48
modedb fb_var_to_videomode: hsync_len : 112
modedb fb_var_to_videomode: left_margin : 248
modedb fb_var_to_videomode: yres : 1024
modedb fb_var_to_videomode: lower_margin : 1
modedb fb_var_to_videomode: vsync_len : 3
modedb fb_var_to_videomode: upper_margin : 38 modedb fb_var_to_videomode: ----- calculated ----- modedb fb_var_to_videomode: pixclock : 108003000
modedb fb_var_to_videomode: htotal : 1688
modedb fb_var_to_videomode: vtotal : 1066
modedb fb_var_to_videomode: hfreq : 63982
modedb fb_var_to_videomode: refresh : 60
/* 20 1280x1024-60 VESA */
{ NULL, 60, 1280, 1024, 9278, 248, 48, 38, 1, 112, 3,
FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT,
FB_VMODE_NONINTERLACED },
mxc_hdmi mxc_hdmi: Non-CEA mode used in HDMI mxc_hdmi mxc_hdmi: hdmi_av_composer modedb fb_var_to_videomode: ----- var -----
modedb fb_var_to_videomode: pixclock : 9278
modedb fb_var_to_videomode: xres : 1280
modedb fb_var_to_videomode: right_margin : 48
modedb fb_var_to_videomode: hsync_len : 112
modedb fb_var_to_videomode: left_margin : 248
modedb fb_var_to_videomode: yres : 1024
modedb fb_var_to_videomode: lower_margin : 1
modedb fb_var_to_videomode: vsync_len : 3
modedb fb_var_to_videomode: upper_margin : 38 modedb fb_var_to_videomode: ----- calculated ----- modedb fb_var_to_videomode: pixclock : 107781000
modedb fb_var_to_videomode: htotal : 1688
modedb fb_var_to_videomode: vtotal : 1066
modedb fb_var_to_videomode: hfreq : 63851
modedb fb_var_to_videomode: refresh : 59 mxc_hdmi mxc_hdmi: final pixclk = 106165072
Hi takaya
i.MX6Q HDMI module conforms to CEA-861-E specification
and supported frequencies/resolutions are described in sect.33.4.3 Supported Video Mode
https://www.nxp.com/docs/en/reference-manual/IMX6DQRM.pdf
Operation with other frequencies/resolutions as 1280x1024 is not guaranteed
(as warned in log "Non-CEA mode used..")
Best regards
igor
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