Implement DMA channel self linking on OMAP1510 using AUTO_INIT and REPEAT flags of the DMA CCR register.
Created against linux-2.6.31-rc5. Tested on Amstrad Delta. Signed-off-by: Janusz Krzysztofik <[email protected]> --- Note: In its current form, enable_lnk() seems not very consistent (ie. result of a conditional assignment is then overwritten unconditionally). As rather different from OMAP1510 that I am familiar with, I am not quite sure how support for other OMAP models should really look like. So I decided to leave it as is and put my bit in a separate block, adding an additional FIXME comment. --- linux-2.6.31-rc5/arch/arm/plat-omap/dma.c.orig 2009-08-07 13:38:02.000000000 +0200 +++ linux-2.6.31-rc5/arch/arm/plat-omap/dma.c 2009-08-10 09:01:41.000000000 +0200 @@ -653,8 +653,21 @@ static inline void enable_lnk(int lch) { u32 l; + if (omap_dma_in_1510_mode()) { + /* only self linking is supported */ + if (dma_chan[lch].next_lch == lch) { + /* set AUTO_INIT | REPEAT bits in CCR */ + l = dma_read(CCR(lch)); + l |= 3 << 8; + dma_write(l, CCR(lch)); + } + return; + } + l = dma_read(CLNK_CTRL(lch)); + /* FIXME: + * this conditional assignment is then overwritten unconditionally */ if (cpu_class_is_omap1()) l &= ~(1 << 14); @@ -675,13 +688,21 @@ static inline void disable_lnk(int lch) { u32 l; - l = dma_read(CLNK_CTRL(lch)); + if (omap_dma_in_1510_mode()) + l = dma_read(CCR(lch)); + else + l = dma_read(CLNK_CTRL(lch)); /* Disable interrupts */ if (cpu_class_is_omap1()) { dma_write(0, CICR(lch)); - /* Set the STOP_LNK bit */ - l |= 1 << 14; + if (omap_dma_in_1510_mode()) { + /* Unset AUTO_INIT & REPEAT bits */ + l &= ~(3 << 8); + } else { + /* Set the STOP_LNK bit */ + l |= 1 << 14; + } } if (cpu_class_is_omap2()) { @@ -690,7 +711,10 @@ static inline void disable_lnk(int lch) l &= ~(1 << 15); } - dma_write(l, CLNK_CTRL(lch)); + if (omap_dma_in_1510_mode()) + dma_write(l, CCR(lch)); + else + dma_write(l, CLNK_CTRL(lch)); dma_chan[lch].flags &= ~OMAP_DMA_ACTIVE; } @@ -928,7 +952,7 @@ void omap_start_dma(int lch) { u32 l; - if (!omap_dma_in_1510_mode() && dma_chan[lch].next_lch != -1) { + if (dma_chan[lch].next_lch != -1) { int next_lch, cur_lch; char dma_chan_link_map[OMAP_DMA4_LOGICAL_DMA_CH_COUNT]; @@ -979,7 +1003,7 @@ void omap_stop_dma(int lch) { u32 l; - if (!omap_dma_in_1510_mode() && dma_chan[lch].next_lch != -1) { + if (dma_chan[lch].next_lch != -1) { int next_lch, cur_lch = lch; char dma_chan_link_map[OMAP_DMA4_LOGICAL_DMA_CH_COUNT]; @@ -1130,7 +1154,7 @@ int omap_dma_running(void) */ void omap_dma_link_lch(int lch_head, int lch_queue) { - if (omap_dma_in_1510_mode()) { + if (omap_dma_in_1510_mode() && (lch_head != lch_queue)) { printk(KERN_ERR "DMA linking is not supported in 1510 mode\n"); BUG(); return; @@ -1152,7 +1176,7 @@ EXPORT_SYMBOL(omap_dma_link_lch); */ void omap_dma_unlink_lch(int lch_head, int lch_queue) { - if (omap_dma_in_1510_mode()) { + if (omap_dma_in_1510_mode() && (lch_head != lch_queue)) { printk(KERN_ERR "DMA linking is not supported in 1510 mode\n"); BUG(); return; @@ -1822,7 +1846,7 @@ static int omap1_dma_handle_ch(int ch) if (unlikely(csr & OMAP_DMA_DROP_IRQ)) printk(KERN_WARNING "DMA synchronization event drop occurred " "with device %d\n", dma_chan[ch].dev_id); - if (likely(csr & OMAP_DMA_BLOCK_IRQ)) + if (likely(csr & OMAP_DMA_BLOCK_IRQ) && (dma_chan[ch].next_lch != ch)) dma_chan[ch].flags &= ~OMAP_DMA_ACTIVE; if (likely(dma_chan[ch].callback != NULL)) dma_chan[ch].callback(ch, csr, dma_chan[ch].data); -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
