bcm2835_sdhci.c: exit DMA if not enough data left to avoid timeout errors
In the DMA case, given we disable the data interrupts, we never seem to get DATA_END. Given we are relying on DMA interrupts we are not using the SDHCI state machine and hence only call into sdhci_platform_will_handle() for the first check of data. We do not call "will handle" for any following round trips of the same transaction if block size * count > BCM_DMA_BLOCK_SIZE. Manually check "left" in the DMA interrupt handler to see if we have at least another full BCM_DMA_BLOCK_SIZE to handle. Without this change we would DMA that and then even start a DMA with left == 0 which would lead to a timeout and error. Now we re-enable data interrupts and return and let the SDHCI generic interrupt handler and state machine pick the SPACE_AVAIL up and then find that it should punt to the pio_handler for the remaining bytes or finish the data transaction. With this change block mode seems to work beyond 7 * 64byte blocks, which worked as it was below BCM_DMA_BLOCK_SIZE. MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D20199
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=348804
@ -539,6 +539,22 @@ bcm_sdhci_dma_intr(int ch, void *arg)
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left = min(BCM_SDHCI_BUFFER_SIZE,
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slot->curcmd->data->len - slot->offset);
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/*
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* If there is less than buffer size outstanding, we would not handle
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* it anymore using DMA if bcm_sdhci_will_handle_transfer() were asked.
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* Re-enable interrupts and return and let the SDHCI state machine
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* finish the job.
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*/
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if (left < BCM_SDHCI_BUFFER_SIZE) {
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/* Re-enable data interrupts. */
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slot->intmask |= SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL |
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SDHCI_INT_DATA_END;
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bcm_sdhci_write_4(slot->bus, slot, SDHCI_SIGNAL_ENABLE,
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slot->intmask);
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mtx_unlock(&slot->mtx);
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return;
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}
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/* DATA END? */
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reg = bcm_sdhci_read_4(slot->bus, slot, SDHCI_INT_STATUS);
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