diff options
author | Peter Ujfalusi <peter.ujfalusi@nokia.com> | 2010-06-03 07:39:33 +0300 |
---|---|---|
committer | Liam Girdwood <lrg@slimlogic.co.uk> | 2010-06-03 16:12:40 +0100 |
commit | 451fd82dc148bd5ac9ed5b19b6915a1afe32b9cb (patch) | |
tree | 0bd09462f284fbdef0ed98f7d05ed4018302f296 /arch/arm/plat-omap/mcbsp.c | |
parent | 0acce82b3dd792c85079ca1f4f7ffd8c82427e0a (diff) |
OMAP3: McBSP: Change the way how the FIFO is handled
Use the actual FIFO size in words as buffer_size on OMAP3.
Change the threshold configuration to use 1 based numbering, when
specifying the allowed threshold maximum or the McBSP threshold value.
Set the default maximum threshold to (buffer_size - 0x10) intialy.
>From users of McBSP, now it is expected to use this method.
Asking for threshold 1 means that the value written to threshold registers
are going to be 0, which means 1 word threshold.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolsfonmicro.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
Diffstat (limited to 'arch/arm/plat-omap/mcbsp.c')
-rw-r--r-- | arch/arm/plat-omap/mcbsp.c | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/arch/arm/plat-omap/mcbsp.c b/arch/arm/plat-omap/mcbsp.c index 8bab0b28b7a3..4ef46047b787 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. |