summaryrefslogtreecommitdiffstats
path: root/arch/arm/plat-omap/mcbsp.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm/plat-omap/mcbsp.c')
-rw-r--r--arch/arm/plat-omap/mcbsp.c30
1 files changed, 20 insertions, 10 deletions
diff --git a/arch/arm/plat-omap/mcbsp.c b/arch/arm/plat-omap/mcbsp.c
index 8bab0b2..4ef4604 100644
--- a/arch/arm/plat-omap/mcbsp.c
+++ b/arch/arm/plat-omap/mcbsp.c
@@ -481,9 +481,9 @@ int omap_st_is_enabled(unsigned int id)
EXPORT_SYMBOL(omap_st_is_enabled);
/*
- * omap_mcbsp_set_tx_threshold configures how to deal
- * with transmit threshold. the threshold value and handler can be
- * configure in here.
+ * omap_mcbsp_set_rx_threshold configures the transmit threshold in words.
+ * The threshold parameter is 1 based, and it is converted (threshold - 1)
+ * for the THRSH2 register.
*/
void omap_mcbsp_set_tx_threshold(unsigned int id, u16 threshold)
{
@@ -498,14 +498,15 @@ void omap_mcbsp_set_tx_threshold(unsigned int id, u16 threshold)
}
mcbsp = id_to_mcbsp_ptr(id);
- MCBSP_WRITE(mcbsp, THRSH2, threshold);
+ if (threshold && threshold <= mcbsp->max_tx_thres)
+ MCBSP_WRITE(mcbsp, THRSH2, threshold - 1);
}
EXPORT_SYMBOL(omap_mcbsp_set_tx_threshold);
/*
- * omap_mcbsp_set_rx_threshold configures how to deal
- * with receive threshold. the threshold value and handler can be
- * configure in here.
+ * omap_mcbsp_set_rx_threshold configures the receive threshold in words.
+ * The threshold parameter is 1 based, and it is converted (threshold - 1)
+ * for the THRSH1 register.
*/
void omap_mcbsp_set_rx_threshold(unsigned int id, u16 threshold)
{
@@ -520,7 +521,8 @@ void omap_mcbsp_set_rx_threshold(unsigned int id, u16 threshold)
}
mcbsp = id_to_mcbsp_ptr(id);
- MCBSP_WRITE(mcbsp, THRSH1, threshold);
+ if (threshold && threshold <= mcbsp->max_rx_thres)
+ MCBSP_WRITE(mcbsp, THRSH1, threshold - 1);
}
EXPORT_SYMBOL(omap_mcbsp_set_rx_threshold);
@@ -1697,8 +1699,16 @@ static inline void __devinit omap34xx_device_init(struct omap_mcbsp *mcbsp)
{
mcbsp->dma_op_mode = MCBSP_DMA_MODE_ELEMENT;
if (cpu_is_omap34xx()) {
- mcbsp->max_tx_thres = max_thres(mcbsp);
- mcbsp->max_rx_thres = max_thres(mcbsp);
+ /*
+ * Initially configure the maximum thresholds to a safe value.
+ * The McBSP FIFO usage with these values should not go under
+ * 16 locations.
+ * If the whole FIFO without safety buffer is used, than there
+ * is a possibility that the DMA will be not able to push the
+ * new data on time, causing channel shifts in runtime.
+ */
+ mcbsp->max_tx_thres = max_thres(mcbsp) - 0x10;
+ mcbsp->max_rx_thres = max_thres(mcbsp) - 0x10;
/*
* REVISIT: Set dmap_op_mode to THRESHOLD as default
* for mcbsp2 instances.
OpenPOWER on IntegriCloud