Other Parts Discussed in Thread: AM3517
I made a customized AM3517 circuit board according to the LogicPD AM3517 EVM developing kit. The hardware of customized board is almost the same to the AM3517 EVM ( except I leave the N22 pin unconnected according to AM3517 datasheet, and the N22 pin is connected to 1.8V on AM3517 EVM). The software is AM35x-OMAP35x-LINUX-PSP-04.02.00.07. The system works well except the LCD part. It seems the DSI_PLL_LOCK is not properly set. I tested DSS_PCLK pin( AE23) of AM3517, the clock frequency on the AM3517 EVM is about 9MHz, but it's only about 1MHz on the customized board. Is there any insight as to what would cause the problem.
I found the source code dealing with the DSI PLL in the file "inux-04.02.00.07\drivers\video\omap2\dss\dsi.c".
if (wait_for_bit_change(DSI_PLL_STATUS, 1, 1) != 1) {
DSSERR("cannot lock PLL\n");
r = -EIO;
goto err;
}
The output text to teminal when system startup is as below:
[ 3.833160] ThumbEE CPU extension supported.
[ 3.855621] Power Management for TI OMAP3.
[ 3.917358] clock: disabling unused clocks to save power
[ 3.989807] omapdss DSI error: cannot lock PLL
[ 3.994720] omapfb omapfb: Failed to enable display 'lcd'
[ 4.008728] omapfb omapfb: failed to setup omapfb
[ 4.013946] omapfb: probe of omapfb failed with error -5
[ 4.026855] rtc-s35390a 1-0030: setting system clock to 2000-01-01 00:00:00 U
TC (946684800)
[ 4.085601] omapdss DSI error: cannot lock PLL
[ 4.090423] omap_vout omap_vout: 'lcd' Display already enabled
[ 4.145782] omapdss DSI error: cannot lock PLL
[ 4.150665] omap_vout omap_vout: 'lcd' Display already enabled
[ 4.156951] omap_vout omap_vout: Buffer Size = 3686400
[ 4.166625] omap_vout omap_vout: : registered and initialized video device 1
[ 4.174194] omap_vout omap_vout: Buffer Size = 3686400
[ 4.182342] mmc0: new high speed SD card at address 1234
[ 4.190551] omap_vout omap_vout: : registered and initialized video device 2
[ 4.202606] mmcblk0: mmc0:1234 SA02G 1.83 GiB