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add comment about using clk_gpout0 enable bit (Fixes #413)

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Joni Kähärä 2021-05-16 18:11:35 +03:00 committed by Luke Wren
parent 607b42006a
commit 5384b6b4d3
1 changed files with 4 additions and 0 deletions
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4
src/rp2_common/hardware_clocks/clocks.c
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@ -70,6 +70,8 @@ bool clock_configure(enum clock_index clk_index, uint32_t src, uint32_t auxsrc,
// propagating when changing aux mux. Note it would be a really bad idea // propagating when changing aux mux. Note it would be a really bad idea
// to do this on one of the glitchless clocks (clk_sys, clk_ref). // to do this on one of the glitchless clocks (clk_sys, clk_ref).
else { else {
// Disable clock. On clk_ref and clk_sys this does nothing,
// all other clocks have the ENABLE bit in the same position.
hw_clear_bits(&clock->ctrl, CLOCKS_CLK_GPOUT0_CTRL_ENABLE_BITS); hw_clear_bits(&clock->ctrl, CLOCKS_CLK_GPOUT0_CTRL_ENABLE_BITS);
if (configured_freq[clk_index] > 0) { if (configured_freq[clk_index] > 0) {
// Delay for 3 cycles of the target clock, for ENABLE propagation. // Delay for 3 cycles of the target clock, for ENABLE propagation.
@ -101,6 +103,8 @@ bool clock_configure(enum clock_index clk_index, uint32_t src, uint32_t auxsrc,
tight_loop_contents(); tight_loop_contents();
} }
// Enable clock. On clk_ref and clk_sys this does nothing,
// all other clocks have the ENABLE bit in the same position.
hw_set_bits(&clock->ctrl, CLOCKS_CLK_GPOUT0_CTRL_ENABLE_BITS); hw_set_bits(&clock->ctrl, CLOCKS_CLK_GPOUT0_CTRL_ENABLE_BITS);
// Now that the source is configured, we can trust that the user-supplied // Now that the source is configured, we can trust that the user-supplied