Re: [PATCH v2 1/4] ARM: davinci: fix cpufreq registration on da850-evm

wt., 26 mar 2019 o 15:00 Adam Ford [off-list ref] napisał(a):

On Fri, Mar 22, 2019 at 8:31 AM Bartosz Golaszewski [off-list ref] wrote:

quoted

From: Bartosz Golaszewski <redacted>

The system_rev variable is never set on davinci and is always 0, so
we're using the default max operating point of 300MHz. The cvdd supply
comes from the tps6507 pmic and the voltage can go all the way to 1.3V
so the maximum supported rate should be 456MHz.

My understanding is that only certain revisions of the silicon can go
to 456MHz.   The L138's Datasheet lists both a 456 and 375 version.  I
cannot find a way to read a register to determine which version of the
silicon is available. Maybe Sekhar can confirm.

Commit 28bd2c341120 ("davinci: am18x/da850/omap-l138 evm: add support
for higher speed grades") mentions the following:

---
U-Boot on the EVM sets up ATAG_REVISION to inform the OS
regarding the speed grade supported by the silicon. We use
this information to pass on the speed grade information to
the SoC code.
---

Should the system_rev somehow reflect that revision? Any way I can check it?

Bart

adam

quoted

Signed-off-by: Bartosz Golaszewski <redacted>
---
 arch/arm/mach-davinci/board-da850-evm.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/arch/arm/mach-davinci/board-da850-evm.c b/arch/arm/mach-davinci/board-da850-evm.c
index 1fdc9283a8c5..58b2a485b527 100644
--- a/arch/arm/mach-davinci/board-da850-evm.c
+++ b/arch/arm/mach-davinci/board-da850-evm.c

@@ -1155,17 +1155,7 @@ static struct edma_rsv_info *da850_edma_rsv[2] = {
 #ifdef CONFIG_CPU_FREQ
 static __init int da850_evm_init_cpufreq(void)
 {
-       switch (system_rev & 0xF) {
-       case 3:
-               da850_max_speed = 456000;
-               break;
-       case 2:
-               da850_max_speed = 408000;
-               break;
-       case 1:
-               da850_max_speed = 372000;
-               break;
-       }
+       da850_max_speed = 456000;

        return da850_register_cpufreq("pll0_sysclk3");
 }
--

2.20.1


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