Re: [PATCH 12/16] clk: renesas: cpg-mssr: Add support for R-Car S4-8

Hi Shimoda-san,

On Mon, Nov 29, 2021 at 9:36 AM Yoshihiro Shimoda
[off-list ref] wrote:

quoted

From: Geert Uytterhoeven, Sent: Wednesday, November 24, 2021 10:48 PM
On Tue, Nov 16, 2021 at 8:42 AM Yoshihiro Shimoda
[off-list ref] wrote:

quoted

Initial support for R-Car S4-8 (r8a779f0), including core, module
clocks, resets, and register access, because register specification
differs from R-Car Gen2/3. The register layout of V3U is a similar
with R-Car S4-8 so that renames CLK_REG_LAYOUT_RCAR_V3U as
CLK_REG_LAYOUT_RCAR_GEN4. However, PLL names differ between V3U
and S4-8.

Inspired by patches in the BSP by LUU HOAI.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

quoted

quoted

+
+       DEF_FIXED(".pll1_div2", CLK_PLL1_DIV2,  CLK_PLL1,       2, 1),
+       DEF_FIXED(".pll2_div2", CLK_PLL2_DIV2,  CLK_PLL2,       2, 1),
+       DEF_FIXED(".pll3_div2", CLK_PLL3_DIV2,  CLK_PLL3,       2, 1),
+       DEF_FIXED(".pll5_div2", CLK_PLL5_DIV2,  CLK_PLL5,       2, 1),
+       DEF_FIXED(".pll5_div4", CLK_PLL5_DIV4,  CLK_PLL5_DIV2,  2, 1),
+       DEF_FIXED(".pll6_div2", CLK_PLL6_DIV2,  CLK_PLL6,       2, 1),
+       DEF_FIXED(".s0",        CLK_S0,         CLK_PLL1_DIV2,  2, 1),
+       DEF_FIXED(".sdsrc",     CLK_SDSRC,      CLK_PLL5_DIV2,  2, 1),

This relies on the default setting of the SD-IF0 Clock Frequency
Control Register 1 (SD0CKCR1)?

You're correct. So, we should not use DEF_FIXED for SDSRC...

You can use DEF_FIXED in the initial version, and add proper SD0CKCR1
support later.
This is similar to the handling of the various PLLs: currently they're
treated as fixed ratio clocks, later they can become programmable by
adding support for the PLLnCR1 registers.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds