Re: [PATCH 2/6] drm: bridge: samsung-dsim: Fix PMS Calculator on imx8m[mnp]

[Marek Vasut]

On 4/15/23 12:40, Adam Ford wrote:
> According to Table 13-45 of the i.MX8M Mini Reference Manual, the min
> and max values for M and  the frequency range for the VCO_out
> calculator were incorrect.  This also appears to be the case for the
> imx8mn and imx8mp.
>
> To fix this, make new variables to hold the min and max values of m
> and the minimum value of VCO_out, and update the PMS calculator to
> use these new variables instead of using hard-coded values to keep
> the backwards compatibility with other parts using this driver.

[...]

>   static const struct samsung_dsim_driver_data imx8mm_dsi_driver_data = {
> @@ -470,6 +485,9 @@ static const struct samsung_dsim_driver_data imx8mm_dsi_driver_data = {
>   	 */
>   	.pll_p_offset = 14,
>   	.reg_values = imx8mm_dsim_reg_values,
> +	.m_min = 64,
> +	.m_max = 1023,
> +	.vco_min = 1050,

You might want to call this 'min_freq' since there is a 'max_freq' which 
seems to indicate what VCO max frequency is.

Note that the same datasheet contains the following information:
"
MIPI_DPHY_M_PLLPMS field descriptions

12–4 PMS_M
Specifies the PLL PMS value for the M divider
NOTE: The programmable divider range should be within 25 to 125 to 
ensure PLL stability.
NOTE: The M and P divider values should be considered together to ensure 
VCO ouput frequency
(VCO_out) range is between 350 MHz to 750 MHz.
Please refer to the topic DPHY PLL for more information.
"