On Fri, Nov 18, 2011 at 12:18 PM, Stephen Warren [off-list ref] wrote:

Olof Johansson wrote at Friday, November 18, 2011 12:07 PM:

quoted

On Thu, Nov 17, 2011 at 06:19:17PM +0200, Peter De Schrijver wrote:

quoted

Rework the tegra20 clock code to support multiple tegra variants :

?* remove tegra2_periph_reset_assert/tegra2_periph_reset_deassert. This
? ?functionality should be in clock.c.
?* compile tegra_sdmmc_tap_delay only on tegra20 as this feature will not
? ?be available in future variants.
?* don't export clk_measure_input_freq as its functionality is also available
? ?using clk_get_rate().

...

quoted

quoted

@@ -403,10 +405,11 @@ void __init tegra_init_clock(void)

?}

?/*
- * The SDMMC controllers have extra bits in the clock source register that
- * adjust the delay between the clock and data to compenstate for delays
- * on the PCB.
+ * The SDMMC controllers on tegra20 have extra bits in the clock source
+ * register that adjust the delay between the clock and data to compenstate
+ * for delays on the PCB.
? */
+#ifdef CONFIG_ARCH_TEGRA_2x_SOC
?void tegra_sdmmc_tap_delay(struct clk *c, int delay)
?{
? ? unsigned long flags;

@@ -415,6 +418,7 @@ void tegra_sdmmc_tap_delay(struct clk *c, int delay)

? ? tegra2_sdmmc_tap_delay(c, delay);
? ? spin_unlock_irqrestore(&c->spinlock, flags);
?}
+#endif

Ifdeffing this out doesn't quite make sense. Better to do a #ifdef in the
include file with an #else case that fills in an empty function. This
needs to be abstracted differently for the two platforms anyway but
that can be done separately from this. Does tegra3 have tap delay setup
as well? (I don't have the TRM handy right now).

I vote just rip this function out altogether.

It isn't used in mainline, chromeos-2.6.38, chromeos-3.0, nor our internal
2.6.36 or 2.6.39 kernels.

Equally, I can't find any documentation of the register bits this code
touches in either Tegra20 or Tegra30 TRMs.

Actually, it used on some of the chromeos platforms, in particular for
the sdio wifi interface (see board-seaboard.c on the chromeos tree).
Without it we don't have stable operation. I'll get the use side
patches posted for it for 3.3.

And yeah. I was unable to find documentation too, it required getting
questions answered from FAEs.


-Olof