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dmaengine: hsu: correct use of channel status register

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There is a typo in documentation regarding to descriptor empty bit (DESCE)
which is set to 1 when descriptor is empty. Thus, status register at the end of
a transfer usually returns all DESCE bits set and thus it will never be zero.

Moreover, there are 2 bits (CDESC) that encode current descriptor, on which
interrupt has been asserted. In case when we have few descriptors programmed we
might have non-zero value.

Remove DESCE and CDESC bits from DMA channel status register (HSU_CH_SR) when
reading it.

Fixes: 2b49e0c56741 ("dmaengine: append hsu DMA driver")
Cc: stable@vger.kernel.org
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Andy Shevchenko 2016-03-18 14:26:32 +02:00 committed by Vinod Koul
parent a197f3c7d4
commit 4f4bc0abff
2 changed files with 4 additions and 1 deletions
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2
drivers/dma/hsu/hsu.c
View File

@ -135,7 +135,7 @@ static u32 hsu_dma_chan_get_sr(struct hsu_dma_chan *hsuc)
sr = hsu_chan_readl(hsuc, HSU_CH_SR);
spin_unlock_irqrestore(&hsuc->vchan.lock, flags);
return sr;
return sr & ~(HSU_CH_SR_DESCE_ANY | HSU_CH_SR_CDESC_ANY);
}
irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip, unsigned short nr)

3
drivers/dma/hsu/hsu.h
View File

@ -41,6 +41,9 @@
#define HSU_CH_SR_DESCTO(x) BIT(8 + (x))
#define HSU_CH_SR_DESCTO_ANY (BIT(11) | BIT(10) | BIT(9) | BIT(8))
#define HSU_CH_SR_CHE BIT(15)
#define HSU_CH_SR_DESCE(x) BIT(16 + (x))
#define HSU_CH_SR_DESCE_ANY (BIT(19) | BIT(18) | BIT(17) | BIT(16))
#define HSU_CH_SR_CDESC_ANY (BIT(31) | BIT(30))
/* Bits in HSU_CH_CR */
#define HSU_CH_CR_CHA BIT(0)