From 94901e1b24496f04bd59176b7f87406e71505e27 Mon Sep 17 00:00:00 2001 From: Alexander Sverdlin Date: Thu, 7 Jan 2016 23:05:48 +0100 Subject: [PATCH] dmaengine: ep93xx: Treat STALL and NFB IRQs same way Debugging ALSA hangups it was found that EP9302 (latest E2 rev.) DMA controller sometimes asserts STALL interrupt instead of NFB interrupt. Simply ignoring the difference and simply acting upon the amount of data we still have to transfer seems to work fine. This somehow sounds similar to M2M issue which is already dealt with in the driver, when the controller asserts DONE interrupt too early. The issue is not documented in Cirrus Logic erratas for EP93XX, but original Cirrus DMA driver from 2003 (not based on DMA API) did the similar handling of STALL interrupt. In-tree driver (6d831c65) did it also, before conversion to DMA engine API. Signed-off-by: Alexander Sverdlin Signed-off-by: Vinod Koul --- drivers/dma/ep93xx_dma.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) diff --git a/drivers/dma/ep93xx_dma.c b/drivers/dma/ep93xx_dma.c index 57ff462..21f08cc 100644 --- a/drivers/dma/ep93xx_dma.c +++ b/drivers/dma/ep93xx_dma.c @@ -421,23 +421,25 @@ static int m2p_hw_interrupt(struct ep93xx_dma_chan *edmac) desc->size); } - switch (irq_status & (M2P_INTERRUPT_STALL | M2P_INTERRUPT_NFB)) { - case M2P_INTERRUPT_STALL: - /* Disable interrupts */ - control = readl(edmac->regs + M2P_CONTROL); - control &= ~(M2P_CONTROL_STALLINT | M2P_CONTROL_NFBINT); - m2p_set_control(edmac, control); - - return INTERRUPT_DONE; - - case M2P_INTERRUPT_NFB: - if (ep93xx_dma_advance_active(edmac)) - m2p_fill_desc(edmac); + /* + * Even latest E2 silicon revision sometimes assert STALL interrupt + * instead of NFB. Therefore we treat them equally, basing on the + * amount of data we still have to transfer. + */ + if (!(irq_status & (M2P_INTERRUPT_STALL | M2P_INTERRUPT_NFB))) + return INTERRUPT_UNKNOWN; + if (ep93xx_dma_advance_active(edmac)) { + m2p_fill_desc(edmac); return INTERRUPT_NEXT_BUFFER; } - return INTERRUPT_UNKNOWN; + /* Disable interrupts */ + control = readl(edmac->regs + M2P_CONTROL); + control &= ~(M2P_CONTROL_STALLINT | M2P_CONTROL_NFBINT); + m2p_set_control(edmac, control); + + return INTERRUPT_DONE; } /* -- 2.7.4