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hange max7456 driver to only perform stall check once a second instead of every drawScreen call

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The max7456 driver performs a "stall check" looking to see if the device had stopped responding. It does this by reading the VM0 register and comparing it to the in-memory version. Presumably if communication failed because the device isn't responding then the result of the SPI transfer would be an unexpected value. If the incorrect value was returned then it would trigger a reinitialization in the hopes of getting the device to respond.

The problem is that this check was happening on **every** call to `displayDrawScreen` unnecessarily. So in the case of the OSD using the max7456 it would happen every 16.7ms (60hz) which is clearly overkill. The unnecessary register check was adding a fixed ~7us to every iteration of the OSD task (along with potential extra bus contention). So now the "stall test" is only performed once a second.
This commit is contained in:
Bruce Luckcuck 2019-10-26 14:47:02 -04:00
parent 13d46c7d84
commit d155dc0ed4
1 changed files with 16 additions and 10 deletions
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26
src/main/drivers/max7456.c
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@ -119,6 +119,7 @@
#define VIN_IS_NTSC_alt(val) (!STAT_IS_LOS(val) && !STAT_IS_PAL(val)) #define VIN_IS_NTSC_alt(val) (!STAT_IS_LOS(val) && !STAT_IS_PAL(val))
#define MAX7456_SIGNAL_CHECK_INTERVAL_MS 1000 // msec #define MAX7456_SIGNAL_CHECK_INTERVAL_MS 1000 // msec
#define MAX7456_STALL_CHECK_INTERVAL_MS 1000 // msec
// DMM special bits // DMM special bits
#define CLEAR_DISPLAY 0x04 #define CLEAR_DISPLAY 0x04
@ -613,19 +614,24 @@ bool max7456BuffersSynced(void)
return true; return true;
} }
void max7456ReInitIfRequired(void) void max7456ReInitIfRequired(bool forceStallCheck)
{ {
static uint32_t lastSigCheckMs = 0; static timeMs_t lastSigCheckMs = 0;
static uint32_t videoDetectTimeMs = 0; static timeMs_t videoDetectTimeMs = 0;
static uint16_t reInitCount = 0; static uint16_t reInitCount = 0;
static timeMs_t lastStallCheckMs = MAX7456_STALL_CHECK_INTERVAL_MS / 2; // offset so that it doesn't coincide with the signal check
__spiBusTransactionBegin(busdev);
const uint8_t stallCheck = max7456Send(MAX7456ADD_VM0|MAX7456ADD_READ, 0x00);
__spiBusTransactionEnd(busdev);
const timeMs_t nowMs = millis(); const timeMs_t nowMs = millis();
if (stallCheck != videoSignalReg) { bool stalled = false;
if (forceStallCheck || (lastStallCheckMs + MAX7456_STALL_CHECK_INTERVAL_MS < nowMs)) {
lastStallCheckMs = nowMs;
__spiBusTransactionBegin(busdev);
stalled = (max7456Send(MAX7456ADD_VM0|MAX7456ADD_READ, 0x00) != videoSignalReg);
__spiBusTransactionEnd(busdev);
}
if (stalled) {
max7456ReInit(); max7456ReInit();
} else if ((videoSignalCfg == VIDEO_SYSTEM_AUTO) } else if ((videoSignalCfg == VIDEO_SYSTEM_AUTO)
&& ((nowMs - lastSigCheckMs) > MAX7456_SIGNAL_CHECK_INTERVAL_MS)) { && ((nowMs - lastSigCheckMs) > MAX7456_SIGNAL_CHECK_INTERVAL_MS)) {
@ -671,7 +677,7 @@ void max7456DrawScreen(void)
// (Re)Initialize MAX7456 at startup or stall is detected. // (Re)Initialize MAX7456 at startup or stall is detected.
max7456ReInitIfRequired(); max7456ReInitIfRequired(false);
int buff_len = 0; int buff_len = 0;
for (int k = 0; k < MAX_CHARS2UPDATE; k++) { for (int k = 0; k < MAX_CHARS2UPDATE; k++) {
@ -751,7 +757,7 @@ void max7456RefreshAll(void)
while (dmaTransactionInProgress); while (dmaTransactionInProgress);
#endif #endif
max7456ReInitIfRequired(); max7456ReInitIfRequired(true);
max7456DrawScreenSlow(); max7456DrawScreenSlow();
} }