-----Original Message----- From: Tom Warren Sent: Thursday, August 20, 2015 9:20 AM To: 'Stephen Warren'; Thierry Reding Cc: Albert Aribaud; u-boot@lists.denx.de; Stephen Warren Subject: RE: [U-Boot] [PATCH 2/6] ARM: tegra: Implement clk_m
Stephen/Thierry,
-----Original Message----- From: Stephen Warren [mailto:swarren@wwwdotorg.org] Sent: Thursday, August 20, 2015 7:59 AM To: Thierry Reding Cc: Albert Aribaud; Tom Warren; u-boot@lists.denx.de; Stephen Warren Subject: Re: [U-Boot] [PATCH 2/6] ARM: tegra: Implement clk_m
On 08/20/2015 03:42 AM, Thierry Reding wrote:
From: Thierry Reding treding@nvidia.com
On currently supported SoCs, clk_m always runs at the same frequency as the oscillator input. However newer SoC generations such as Tegra210 no longer have that restriction. Prepare for that by separating clk_m from the oscillator clock and allow SoC code to override
the clk_m rate.
diff --git a/arch/arm/include/asm/arch-tegra114/clock-tables.h b/arch/arm/include/asm/arch-tegra114/clock-tables.h index d8fa0e1d2cee..3f910f5ae8b9 100644 --- a/arch/arm/include/asm/arch-tegra114/clock-tables.h +++ b/arch/arm/include/asm/arch-tegra114/clock-tables.h @@ -38,6 +38,7 @@ enum clock_id { /* These are the base clocks (inputs to the Tegra SOC) */ CLOCK_ID_32KHZ, CLOCK_ID_OSC,
CLOCK_ID_CLK_M,
CLOCK_ID_COUNT, /* number of PLLs */ CLOCK_ID_DISPLAY2, /* placeholder */
clock.h contains the following:
/* Number of PLL-based clocks (i.e. not OSC or 32KHz) */ #define CLOCK_ID_PLL_COUNT (CLOCK_ID_COUNT - 2)
I decremented the CLOCK_ID_COUNT for my pllinfo tables, since 32KHZ and OSC have no PLL params that can be configured, to remove the 2 extra, empty table entries. We can either remove it, and add 2 empty entries for OSC/32KHZ in all the pllinfo tables (per SoC), and then add new CLOCK_ID entries wherever, or have a rule that new entries here need to be above ID_32KHZ for any PLL needing dividers, etc., and below it for any static clock like OSC, 32KHz, etc. Of course, we'll need to keep track of the decrement depending on how many IDs are added and where. Might be easier to just have an entry for every CLOCK_ID, regardless.
I applied Thierry's patchset and found that adding CLK_M to the CLOCK_ID tables results in an extra empty pll_info_table entry (3 32-bit words) for each SoC.
So I can leave it as-is, or I can adjust CLOCK_ID_PLL_COUNT in clock.h to be CLOCK_ID_COUNT - 3 to account for the 3 non-configurable clocks (OSC, 32KHz and MCLK), and there'll be no extra empty data in the pll_info tables.
I'm going to go with the 2nd approach. I've applied these (plus some from Stephen and one from Axel Lin) to u-boot-tegra/next and after some testing today I'll be pushing this to Denx for everyone to play with it before I send a PR to TomR. So PTAL.
Thanks
Tom -- nvpublic
... which would need to be updated. Related, see internal bug number 1676978 to see if any of the other gotchas there affect this patch.