Thierry Reding wrote at Saturday, March 03, 2012 3:48 PM: > * Stephen Warren wrote: > > Thierry Reding wrote at Wednesday, February 22, 2012 8:17 AM: > > > PWM clock source registers in Tegra 2 have different clock source selection bit > > > fields than other registers. PWM clock source bits in CLK_SOURCE_PWM_0 register > > > are located at bit field bit[30:28] while others are at bit field bit[31:30] in > > > their respective clock source register. > > > > > > This patch updates the clock programming to correctly reflect that, by adding a > > > flag to indicate the alternate bit field format and checking for it when > > > selecting a clock source (parent clock). > > > > tegra30_clocks.c needs this change too, although on Tegra30, it's bits > > 29:28 for the PWM, and bits 31:30 for non-PWM. > > Okay, I'll add code for Tegra30 in the next version. I won't be able to test > that at all because I don't have any Tegra30 hardware. It looks like Tegra30 is already taken care of; see periph_clk_source_mask() in tegra30_clocks.c, assuming that tegra_list_clks[] has the correct flags set of each entry anyway. PWM does at least. > > > diff --git a/arch/arm/mach-tegra/tegra2_clocks.c b/arch/arm/mach-tegra/tegra2_clocks.c > > > > +#define PERIPH_CLK_SOURCE_4BIT_MASK (7<<28) > > +#define PERIPH_CLK_SOURCE_4BIT_SHIFT 28 > > > > Why is this (and the flag that enables it) called "4 bit"; the existing > > code supports a 2-bit mux field (4-values), whereas this new code supports > > a 3-bit field (potentially 8 values, but only 5 actually assigned). > > Can this be renamed something more accurate, especially since on Tegra30 > > the difference is only the bit position of the field, not the number of > > bits in the field. > > This is taken directly from the Chromium tree, so I don't really know why > that name was chosen. But since the PWM clock source register seems to be the > only exception, how about calling the flag PWM_CLK and prefix the shift and > mask with PWM_CLK_SOURCE_ instead? That sounds reasonable. -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
