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dmaengine: omap-dma: cleanup errata 3.3 handling

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Provide a function to read the CSAC/CDAC register, working around the
OMAP 3.2/3.3 erratum (which requires two reads of the register if the
first returned zero.

Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2013-11-06 19:26:45 +00:00
parent c5ed98b6ae
commit b07fd625ac
1 changed files with 29 additions and 23 deletions
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52
drivers/dma/omap-dma.c
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@ -451,28 +451,39 @@ static size_t omap_dma_desc_size_pos(struct omap_desc *d, dma_addr_t addr)
return size; return size;
} }
/*
* OMAP 3.2/3.3 erratum: sometimes 0 is returned if CSAC/CDAC is
* read before the DMA controller finished disabling the channel.
*/
static uint32_t omap_dma_chan_read_3_3(struct omap_chan *c, unsigned reg)
{
struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device);
uint32_t val;
val = omap_dma_chan_read(c, reg);
if (val == 0 && od->plat->errata & DMA_ERRATA_3_3)
val = omap_dma_chan_read(c, reg);
return val;
}
static dma_addr_t omap_dma_get_src_pos(struct omap_chan *c) static dma_addr_t omap_dma_get_src_pos(struct omap_chan *c)
{ {
struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device); struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device);
dma_addr_t addr; dma_addr_t addr, cdac;
if (__dma_omap15xx(od->plat->dma_attr)) if (__dma_omap15xx(od->plat->dma_attr)) {
addr = omap_dma_chan_read(c, CPC); addr = omap_dma_chan_read(c, CPC);
else } else {
addr = omap_dma_chan_read(c, CSAC); addr = omap_dma_chan_read_3_3(c, CSAC);
cdac = omap_dma_chan_read_3_3(c, CDAC);
if (od->plat->errata & DMA_ERRATA_3_3 && addr == 0)
addr = omap_dma_chan_read(c, CSAC);
if (!__dma_omap15xx(od->plat->dma_attr)) {
/* /*
* CDAC == 0 indicates that the DMA transfer on the channel has * CDAC == 0 indicates that the DMA transfer on the channel has
* not been started (no data has been transferred so far). * not been started (no data has been transferred so far).
* Return the programmed source start address in this case. * Return the programmed source start address in this case.
*/ */
if (omap_dma_chan_read(c, CDAC)) if (cdac == 0)
addr = omap_dma_chan_read(c, CSAC);
else
addr = omap_dma_chan_read(c, CSSA); addr = omap_dma_chan_read(c, CSSA);
} }
@ -487,21 +498,16 @@ static dma_addr_t omap_dma_get_dst_pos(struct omap_chan *c)
struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device); struct omap_dmadev *od = to_omap_dma_dev(c->vc.chan.device);
dma_addr_t addr; dma_addr_t addr;
if (__dma_omap15xx(od->plat->dma_attr)) if (__dma_omap15xx(od->plat->dma_attr)) {
addr = omap_dma_chan_read(c, CPC); addr = omap_dma_chan_read(c, CPC);
else } else {
addr = omap_dma_chan_read(c, CDAC); addr = omap_dma_chan_read_3_3(c, CDAC);
/*
* omap 3.2/3.3 erratum: sometimes 0 is returned if CSAC/CDAC is
* read before the DMA controller finished disabling the channel.
*/
if (!__dma_omap15xx(od->plat->dma_attr) && addr == 0) {
addr = omap_dma_chan_read(c, CDAC);
/* /*
* CDAC == 0 indicates that the DMA transfer on the channel has * CDAC == 0 indicates that the DMA transfer on the channel
* not been started (no data has been transferred so far). * has not been started (no data has been transferred so
* Return the programmed destination start address in this case. * far). Return the programmed destination start address in
* this case.
*/ */
if (addr == 0) if (addr == 0)
addr = omap_dma_chan_read(c, CDSA); addr = omap_dma_chan_read(c, CDSA);