From 96fbd74551e9cae8fd5e9cb62a0a19336a3064fa Mon Sep 17 00:00:00 2001 From: Janusz Krzysztofik Date: Mon, 15 Feb 2010 10:03:33 -0800 Subject: omap: McBSP: Use cache when modifying individual register bits Change the way McBSP registers are updated: use cached values instead of relying upon those read back from the device. With this patch, I have finally managed to get rid of all random playback/recording hangups on my OMAP1510 based Amstrad Delta hardware. Before that, values read back from McBSP registers to be used for updating them happened to be errornous. From the hardware side, the issue appeared to be caused by a relatively high power requirements of an external USB adapter connected to the board's printer dedicated USB port. I think there is one important point that makes this patch worth of applying, apart from my hardware quality. With the current code, if it ever happens to any machine, no matter if OMAP1510 or newer, to read incorrect value from a McBSP register, this wrong value will get written back without any checking. That can lead to hardware damage if, for example, an input pin is turned into output as a result. Applies on top of patch 3 from this series: [PATCH v9 3/4] OMAP: McBSP: Introduce caching in register write operations Tested on OMAP1510 based Amstrad Delta using linux-omap for-next, commit fb7380d70e041e4b3892f6b19dff7efb609d15a4 (2.6.33-rc3+ dated 2010-01-11). Compile-tested with omap_3430sdp_defconfig. Signed-off-by: Janusz Krzysztofik Acked-by: Peter Ujfalusi Acked-by: Jarkko Nikula Signed-off-by: Tony Lindgren --- arch/arm/plat-omap/mcbsp.c | 78 ++++++++++++++++++++++++++++------------------ 1 file changed, 47 insertions(+), 31 deletions(-) (limited to 'arch') diff --git a/arch/arm/plat-omap/mcbsp.c b/arch/arm/plat-omap/mcbsp.c index 61e440a0f7cd..473be3dc2cf5 100644 --- a/arch/arm/plat-omap/mcbsp.c +++ b/arch/arm/plat-omap/mcbsp.c @@ -114,7 +114,8 @@ static irqreturn_t omap_mcbsp_tx_irq_handler(int irq, void *dev_id) dev_err(mcbsp_tx->dev, "TX Frame Sync Error! : 0x%x\n", irqst_spcr2); /* Writing zero to XSYNC_ERR clears the IRQ */ - MCBSP_WRITE(mcbsp_tx, SPCR2, irqst_spcr2 & ~(XSYNC_ERR)); + MCBSP_WRITE(mcbsp_tx, SPCR2, + MCBSP_READ_CACHE(mcbsp_tx, SPCR2) & ~(XSYNC_ERR)); } else { complete(&mcbsp_tx->tx_irq_completion); } @@ -134,7 +135,8 @@ static irqreturn_t omap_mcbsp_rx_irq_handler(int irq, void *dev_id) dev_err(mcbsp_rx->dev, "RX Frame Sync Error! : 0x%x\n", irqst_spcr1); /* Writing zero to RSYNC_ERR clears the IRQ */ - MCBSP_WRITE(mcbsp_rx, SPCR1, irqst_spcr1 & ~(RSYNC_ERR)); + MCBSP_WRITE(mcbsp_rx, SPCR1, + MCBSP_READ_CACHE(mcbsp_rx, SPCR1) & ~(RSYNC_ERR)); } else { complete(&mcbsp_rx->tx_irq_completion); } @@ -544,24 +546,25 @@ void omap_mcbsp_start(unsigned int id, int tx, int rx) } mcbsp = id_to_mcbsp_ptr(id); - mcbsp->rx_word_length = (MCBSP_READ(mcbsp, RCR1) >> 5) & 0x7; - mcbsp->tx_word_length = (MCBSP_READ(mcbsp, XCR1) >> 5) & 0x7; + mcbsp->rx_word_length = (MCBSP_READ_CACHE(mcbsp, RCR1) >> 5) & 0x7; + mcbsp->tx_word_length = (MCBSP_READ_CACHE(mcbsp, XCR1) >> 5) & 0x7; - idle = !((MCBSP_READ(mcbsp, SPCR2) | MCBSP_READ(mcbsp, SPCR1)) & 1); + idle = !((MCBSP_READ_CACHE(mcbsp, SPCR2) | + MCBSP_READ_CACHE(mcbsp, SPCR1)) & 1); if (idle) { /* Start the sample generator */ - w = MCBSP_READ(mcbsp, SPCR2); + w = MCBSP_READ_CACHE(mcbsp, SPCR2); MCBSP_WRITE(mcbsp, SPCR2, w | (1 << 6)); } /* Enable transmitter and receiver */ tx &= 1; - w = MCBSP_READ(mcbsp, SPCR2); + w = MCBSP_READ_CACHE(mcbsp, SPCR2); MCBSP_WRITE(mcbsp, SPCR2, w | tx); rx &= 1; - w = MCBSP_READ(mcbsp, SPCR1); + w = MCBSP_READ_CACHE(mcbsp, SPCR1); MCBSP_WRITE(mcbsp, SPCR1, w | rx); /* @@ -574,16 +577,16 @@ void omap_mcbsp_start(unsigned int id, int tx, int rx) if (idle) { /* Start frame sync */ - w = MCBSP_READ(mcbsp, SPCR2); + w = MCBSP_READ_CACHE(mcbsp, SPCR2); MCBSP_WRITE(mcbsp, SPCR2, w | (1 << 7)); } if (cpu_is_omap2430() || cpu_is_omap34xx()) { /* Release the transmitter and receiver */ - w = MCBSP_READ(mcbsp, XCCR); + w = MCBSP_READ_CACHE(mcbsp, XCCR); w &= ~(tx ? XDISABLE : 0); MCBSP_WRITE(mcbsp, XCCR, w); - w = MCBSP_READ(mcbsp, RCCR); + w = MCBSP_READ_CACHE(mcbsp, RCCR); w &= ~(rx ? RDISABLE : 0); MCBSP_WRITE(mcbsp, RCCR, w); } @@ -609,28 +612,29 @@ void omap_mcbsp_stop(unsigned int id, int tx, int rx) /* Reset transmitter */ tx &= 1; if (cpu_is_omap2430() || cpu_is_omap34xx()) { - w = MCBSP_READ(mcbsp, XCCR); + w = MCBSP_READ_CACHE(mcbsp, XCCR); w |= (tx ? XDISABLE : 0); MCBSP_WRITE(mcbsp, XCCR, w); } - w = MCBSP_READ(mcbsp, SPCR2); + w = MCBSP_READ_CACHE(mcbsp, SPCR2); MCBSP_WRITE(mcbsp, SPCR2, w & ~tx); /* Reset receiver */ rx &= 1; if (cpu_is_omap2430() || cpu_is_omap34xx()) { - w = MCBSP_READ(mcbsp, RCCR); + w = MCBSP_READ_CACHE(mcbsp, RCCR); w |= (rx ? RDISABLE : 0); MCBSP_WRITE(mcbsp, RCCR, w); } - w = MCBSP_READ(mcbsp, SPCR1); + w = MCBSP_READ_CACHE(mcbsp, SPCR1); MCBSP_WRITE(mcbsp, SPCR1, w & ~rx); - idle = !((MCBSP_READ(mcbsp, SPCR2) | MCBSP_READ(mcbsp, SPCR1)) & 1); + idle = !((MCBSP_READ_CACHE(mcbsp, SPCR2) | + MCBSP_READ_CACHE(mcbsp, SPCR1)) & 1); if (idle) { /* Reset the sample rate generator */ - w = MCBSP_READ(mcbsp, SPCR2); + w = MCBSP_READ_CACHE(mcbsp, SPCR2); MCBSP_WRITE(mcbsp, SPCR2, w & ~(1 << 6)); } } @@ -653,7 +657,7 @@ int omap_mcbsp_pollwrite(unsigned int id, u16 buf) if (MCBSP_READ(mcbsp, SPCR2) & XSYNC_ERR) { /* clear error */ MCBSP_WRITE(mcbsp, SPCR2, - MCBSP_READ(mcbsp, SPCR2) & (~XSYNC_ERR)); + MCBSP_READ_CACHE(mcbsp, SPCR2) & (~XSYNC_ERR)); /* resend */ return -1; } else { @@ -662,10 +666,12 @@ int omap_mcbsp_pollwrite(unsigned int id, u16 buf) while (!(MCBSP_READ(mcbsp, SPCR2) & XRDY)) { if (attemps++ > 1000) { MCBSP_WRITE(mcbsp, SPCR2, - MCBSP_READ(mcbsp, SPCR2) & (~XRST)); + MCBSP_READ_CACHE(mcbsp, SPCR2) & + (~XRST)); udelay(10); MCBSP_WRITE(mcbsp, SPCR2, - MCBSP_READ(mcbsp, SPCR2) | (XRST)); + MCBSP_READ_CACHE(mcbsp, SPCR2) | + (XRST)); udelay(10); dev_err(mcbsp->dev, "Could not write to" " McBSP%d Register\n", mcbsp->id); @@ -692,7 +698,7 @@ int omap_mcbsp_pollread(unsigned int id, u16 *buf) if (MCBSP_READ(mcbsp, SPCR1) & RSYNC_ERR) { /* clear error */ MCBSP_WRITE(mcbsp, SPCR1, - MCBSP_READ(mcbsp, SPCR1) & (~RSYNC_ERR)); + MCBSP_READ_CACHE(mcbsp, SPCR1) & (~RSYNC_ERR)); /* resend */ return -1; } else { @@ -701,10 +707,12 @@ int omap_mcbsp_pollread(unsigned int id, u16 *buf) while (!(MCBSP_READ(mcbsp, SPCR1) & RRDY)) { if (attemps++ > 1000) { MCBSP_WRITE(mcbsp, SPCR1, - MCBSP_READ(mcbsp, SPCR1) & (~RRST)); + MCBSP_READ_CACHE(mcbsp, SPCR1) & + (~RRST)); udelay(10); MCBSP_WRITE(mcbsp, SPCR1, - MCBSP_READ(mcbsp, SPCR1) | (RRST)); + MCBSP_READ_CACHE(mcbsp, SPCR1) | + (RRST)); udelay(10); dev_err(mcbsp->dev, "Could not read from" " McBSP%d Register\n", mcbsp->id); @@ -790,9 +798,11 @@ int omap_mcbsp_spi_master_xmit_word_poll(unsigned int id, u32 word) spcr2 = MCBSP_READ(mcbsp, SPCR2); if (attempts++ > 1000) { /* We must reset the transmitter */ - MCBSP_WRITE(mcbsp, SPCR2, spcr2 & (~XRST)); + MCBSP_WRITE(mcbsp, SPCR2, + MCBSP_READ_CACHE(mcbsp, SPCR2) & (~XRST)); udelay(10); - MCBSP_WRITE(mcbsp, SPCR2, spcr2 | XRST); + MCBSP_WRITE(mcbsp, SPCR2, + MCBSP_READ_CACHE(mcbsp, SPCR2) | XRST); udelay(10); dev_err(mcbsp->dev, "McBSP%d transmitter not " "ready\n", mcbsp->id); @@ -811,9 +821,11 @@ int omap_mcbsp_spi_master_xmit_word_poll(unsigned int id, u32 word) spcr1 = MCBSP_READ(mcbsp, SPCR1); if (attempts++ > 1000) { /* We must reset the receiver */ - MCBSP_WRITE(mcbsp, SPCR1, spcr1 & (~RRST)); + MCBSP_WRITE(mcbsp, SPCR1, + MCBSP_READ_CACHE(mcbsp, SPCR1) & (~RRST)); udelay(10); - MCBSP_WRITE(mcbsp, SPCR1, spcr1 | RRST); + MCBSP_WRITE(mcbsp, SPCR1, + MCBSP_READ_CACHE(mcbsp, SPCR1) | RRST); udelay(10); dev_err(mcbsp->dev, "McBSP%d receiver not " "ready\n", mcbsp->id); @@ -857,9 +869,11 @@ int omap_mcbsp_spi_master_recv_word_poll(unsigned int id, u32 *word) spcr2 = MCBSP_READ(mcbsp, SPCR2); if (attempts++ > 1000) { /* We must reset the transmitter */ - MCBSP_WRITE(mcbsp, SPCR2, spcr2 & (~XRST)); + MCBSP_WRITE(mcbsp, SPCR2, + MCBSP_READ_CACHE(mcbsp, SPCR2) & (~XRST)); udelay(10); - MCBSP_WRITE(mcbsp, SPCR2, spcr2 | XRST); + MCBSP_WRITE(mcbsp, SPCR2, + MCBSP_READ_CACHE(mcbsp, SPCR2) | XRST); udelay(10); dev_err(mcbsp->dev, "McBSP%d transmitter not " "ready\n", mcbsp->id); @@ -878,9 +892,11 @@ int omap_mcbsp_spi_master_recv_word_poll(unsigned int id, u32 *word) spcr1 = MCBSP_READ(mcbsp, SPCR1); if (attempts++ > 1000) { /* We must reset the receiver */ - MCBSP_WRITE(mcbsp, SPCR1, spcr1 & (~RRST)); + MCBSP_WRITE(mcbsp, SPCR1, + MCBSP_READ_CACHE(mcbsp, SPCR1) & (~RRST)); udelay(10); - MCBSP_WRITE(mcbsp, SPCR1, spcr1 | RRST); + MCBSP_WRITE(mcbsp, SPCR1, + MCBSP_READ_CACHE(mcbsp, SPCR1) | RRST); udelay(10); dev_err(mcbsp->dev, "McBSP%d receiver not " "ready\n", mcbsp->id); -- cgit v1.2.1