From: Andy Shevchenko Date: Fri, 18 Mar 2016 12:26:32 +0000 (+0200) Subject: dmaengine: hsu: correct use of channel status register X-Git-Tag: firefly_0821_release~176^2~4^2~48^2~141 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=34c1b030296c6815c05e416c7a647b68e695004a;p=firefly-linux-kernel-4.4.55.git dmaengine: hsu: correct use of channel status register commit 4f4bc0abff79dc9d7ccbd3143adbf8ad1f4fe6ab upstream. 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") Signed-off-by: Andy Shevchenko Signed-off-by: Vinod Koul Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/dma/hsu/hsu.c b/drivers/dma/hsu/hsu.c index 823ad728aecf..efc02b98e6ba 100644 --- a/drivers/dma/hsu/hsu.c +++ b/drivers/dma/hsu/hsu.c @@ -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) diff --git a/drivers/dma/hsu/hsu.h b/drivers/dma/hsu/hsu.h index f06579c6d548..26da2865b025 100644 --- a/drivers/dma/hsu/hsu.h +++ b/drivers/dma/hsu/hsu.h @@ -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)