Commit 7314dec9 authored by Francisco Jerez's avatar Francisco Jerez Committed by Ben Skeggs
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drm/nv17-nv4x: Fix analog load detection false positive on rare occasions.



On some boards the residual current DAC outputs can draw when they're
disconnected can be high enough to give a false load detection
positive (I've only seen it in the S-video luma output of some cards,
but just to be sure). The output line capacitance is limited and
sampling twice should fix it reliably.

Signed-off-by: default avatarFrancisco Jerez <currojerez@riseup.net>
Signed-off-by: default avatarBen Skeggs <bskeggs@redhat.com>
parent 9d59e8a1
......@@ -291,6 +291,8 @@ uint32_t nv17_dac_sample_load(struct drm_encoder *encoder)
msleep(5);
sample = NVReadRAMDAC(dev, 0, NV_PRAMDAC_TEST_CONTROL + regoffset);
/* do it again just in case it's a residual current */
sample &= NVReadRAMDAC(dev, 0, NV_PRAMDAC_TEST_CONTROL + regoffset);
temp = NVReadRAMDAC(dev, head, NV_PRAMDAC_TEST_CONTROL);
NVWriteRAMDAC(dev, head, NV_PRAMDAC_TEST_CONTROL,
......
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