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mmc: dw_mmc: clear TXDR/RXDR ints before enabling 

DMA is only used for transactions exceeding a certain length, otherwise
PIO is used. The TXDR and RXDR interrupts are masked when in DMA mode
but still fire. When switching to PIO mode (e.g. to get SCR field when
an SD card is inserted) these interrupts are not cleared and so they
trigger the ISR as soon as they are unmasked. If the previous DMA did a
write, then the ISR will handle the TXDR interrupt even if the
transaction is a read, completing the transaction without modifying the
read buffer.

This is fixed primarily by clearing these two interrupts before
unmasking them when setting up PIO mode, and also by making the ISR more
robust by only handling TXDR/RXDR in the correct read/write direction.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
James Hogan 2011-06-24 13:54:06 +01:00 committed by Chris Ball
parent 973ed3af1a
commit b40af3aa77
1 changed files with 3 additions and 2 deletions
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5
drivers/mmc/host/dw_mmc.c
View File

@ -497,6 +497,7 @@ static void dw_mci_submit_data(struct dw_mci *host, struct mmc_data *data)
else
host->dir_status = DW_MCI_SEND_STATUS;
mci_writel(host, RINTSTS, SDMMC_INT_TXDR | SDMMC_INT_RXDR);
temp = mci_readl(host, INTMASK);
temp |= SDMMC_INT_TXDR | SDMMC_INT_RXDR;
mci_writel(host, INTMASK, temp);
@ -1230,13 +1231,13 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
if (pending & SDMMC_INT_RXDR) {
mci_writel(host, RINTSTS, SDMMC_INT_RXDR);
if (host->sg)
if (host->dir_status == DW_MCI_RECV_STATUS && host->sg)
dw_mci_read_data_pio(host);
}
if (pending & SDMMC_INT_TXDR) {
mci_writel(host, RINTSTS, SDMMC_INT_TXDR);
if (host->sg)
if (host->dir_status == DW_MCI_SEND_STATUS && host->sg)
dw_mci_write_data_pio(host);
}