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drm: bridge/dw_hdmi: avoid being recursive in N calculation

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There's no need to be recursive when computing the N value for the ACR
packet - we can instead calculate the multiplier prior to our switch()
based lookup, and multiply the N value appropriately afterwards.

Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2015-07-22 10:35:41 +01:00
parent 91cd69088e
commit d0c96d1680
1 changed files with 9 additions and 16 deletions
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25
drivers/gpu/drm/bridge/dw_hdmi.c
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@ -221,6 +221,12 @@ static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk,
unsigned int ratio)
{
unsigned int n = (128 * freq) / 1000;
unsigned int mult = 1;
while (freq > 48000) {
mult *= 2;
freq /= 2;
}
switch (freq) {
case 32000:
@ -232,6 +238,7 @@ static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk,
n = 11648;
else
n = 4096;
n *= mult;
break;
case 44100:
@ -243,6 +250,7 @@ static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk,
n = (ratio == 150) ? 17836 : 8918;
else
n = 6272;
n *= mult;
break;
case 48000:
@ -256,22 +264,7 @@ static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk,
n = (ratio == 150) ? 11648 : 5824;
else
n = 6144;
break;
case 88200:
n = hdmi_compute_n(44100, pixel_clk, ratio) * 2;
break;
case 96000:
n = hdmi_compute_n(48000, pixel_clk, ratio) * 2;
break;
case 176400:
n = hdmi_compute_n(44100, pixel_clk, ratio) * 4;
break;
case 192000:
n = hdmi_compute_n(48000, pixel_clk, ratio) * 4;
n *= mult;
break;
default: