| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.5 028/200] dmaengine: hsu: correct use of channel status register | Date | Mon, 2 May 2016 17:10:27 -0700 |
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4.5-stable review patch. If anyone has any objections, please let me know.
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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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 <andriy.shevchenko@linux.intel.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/dma/hsu/hsu.c | 2 +- drivers/dma/hsu/hsu.h | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/dma/hsu/hsu.c +++ b/drivers/dma/hsu/hsu.c @@ -135,7 +135,7 @@ static u32 hsu_dma_chan_get_sr(struct hs 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) --- 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)
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