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sdcard: run an SD card on SPI at the fast bus speed when it has the bus to itself #12130

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sdcard: run an SD card on SPI at the fast bus speed when it has the bus to itself #12130

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20 changes: 18 additions & 2 deletions src/main/drivers/sdcard/sdcard_spi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,10 +48,22 @@
/* Break up 512-byte SD card sectors into chunks of this size to reduce the peak overhead per call to sdcard_poll(). */
#define SDCARD_BLOCK_CHUNK_SIZE 128

// FAST stays under the 25 MHz of an SD card's default speed on every MCU with an SD card on SPI
#ifndef SDCARD_BUS_SPEED
#define SDCARD_BUS_SPEED BUS_SPEED_STANDARD
#define SDCARD_BUS_SPEED BUS_SPEED_FAST
#endif

// Other devices set their bus speed once, at init, and the bus keeps the last one: a shared bus stays as it was
static bool sdcardSpi_busShared(void)
{
for (const busDeviceDescriptor_t * descriptor = __busdev_registry_start; descriptor < __busdev_registry_end; descriptor++) {
if (descriptor->busType == BUSTYPE_SPI && descriptor->devHwType != DEVHW_SDCARD && descriptor->busdev.spi.spiBus == sdcard.dev->busdev.spi.spiBus) {
return true;
}
}
return false;
}

static void sdcardSpi_select(void)
{
busSelectDevice(sdcard.dev);
Expand Down Expand Up @@ -104,6 +116,10 @@ static void sdcardSpi_reset(void)
if (sdcard.failureCount >= SDCARD_MAX_CONSECUTIVE_FAILURES) {
sdcard.state = SDCARD_STATE_NOT_PRESENT;
} else {
// After an error the card is identified again at the speed it always was, not at the full speed
if (sdcard.state >= SDCARD_STATE_READY) {
busSetSpeed(sdcard.dev, BUS_SPEED_STANDARD);
}
sdcard.operationStartTime = millis();
sdcard.state = SDCARD_STATE_RESET;
}
Expand Down Expand Up @@ -535,7 +551,7 @@ static bool sdcardSpi_poll(void)
}

// Now we're done with init and we can switch to the full speed clock (<25MHz)
busSetSpeed(sdcard.dev, SDCARD_BUS_SPEED);
busSetSpeed(sdcard.dev, sdcardSpi_busShared() ? BUS_SPEED_STANDARD : SDCARD_BUS_SPEED);

sdcard.multiWriteBlocksRemain = 0;

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