0005353: [MIPI sec-dsim] Print warning, if lcdif clock and MIPI DSI clocks do not have a sufficient gap

ID	Project	Category	View Status	Date Submitted	Last Update

0005353	fsimx_Linux	Kernel	public	2022-05-06 08:30	2022-05-06 08:30

Reporter	gerbach	Assigned To
Priority	normal	Severity	feature	Reproducibility	always
Status	new	Resolution	open
Product Version	fsimx8mm-Y2021.04
Target Version	fsimx7ulp-Y2022.05

Summary	0005353: [MIPI sec-dsim] Print warning, if lcdif clock and MIPI DSI clocks do not have a sufficient gap
Description	On SoCs with sec-dsim mipi, the MIPI DSI clock must be higher than the lcdif clock or else the image is fragmented or not shown at all. Both clocks get computed from the same clock configuration in the device tree, but the lcdif clock just gets divided down form the 596MHz video clock, where as the MIPI-DSI clock ist generated by precisely by an own PLL. So it may happen that the MIPI-DSI clock is slower than the lcdif clock and no picture is shown at all. First experiments showd, that with an 66 MHz lcdif clock the MIPI-DSI clock must be at least 1.2MHz faster than the lcdif clock. At 33 MHz the MIPI-DSI clock must be at least 500KHz faster. Implement a warningin the sec-dsim driver, that reads out the lcdif speed an warns if the compute MIPI-DSI clock may not be fast enough. The exact values still have to be determined.

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