lkml.org 
[lkml]   [2023]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 2/6] drm: bridge: samsung-dsim: Fix PMS Calculator on imx8m[mnp]
From
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.
"

\
 
 \ /
  Last update: 2023-04-17 00:07    [W:0.127 / U:0.376 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site