On Mon, Aug 05, 2024 at 07:34:46PM +0530, Mrinmay Sarkar wrote:
On 8/2/2024 6:04 AM, Serge Semin wrote:
On Tue, Jul 23, 2024 at 06:49:32PM +0530, Mrinmay Sarkar wrote:
DW_HDMA_V0_LIE and DW_HDMA_V0_RIE are initialized as BIT(3) and BIT(4) respectively in dw_hdma_control enum. But as per HDMA register these bits are corresponds to LWIE and RWIE bit i.e local watermark interrupt enable and remote watermarek interrupt enable. In linked list mode LWIE and RWIE bits only enable the local and remote watermark interrupt.
Since the watermark interrupts are not used but enabled, this leads to spurious interrupts getting generated. So remove the code that enables them to avoid generating spurious watermark interrupts.
And also rename DW_HDMA_V0_LIE to DW_HDMA_V0_LWIE and DW_HDMA_V0_RIE to DW_HDMA_V0_RWIE as there is no LIE and RIE bits in HDMA and those bits are corresponds to LWIE and RWIE bits.
Fixes: e74c39573d35 ("dmaengine: dw-edma: Add support for native HDMA") cc: stable@vger.kernel.org Signed-off-by: Mrinmay Sarkar quic_msarkar@quicinc.com
drivers/dma/dw-edma/dw-hdma-v0-core.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-)
diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c index fa89b3a..9ad2e28 100644 --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c @@ -17,8 +17,8 @@ enum dw_hdma_control { DW_HDMA_V0_CB = BIT(0), DW_HDMA_V0_TCB = BIT(1), DW_HDMA_V0_LLP = BIT(2),
- DW_HDMA_V0_LIE = BIT(3),
- DW_HDMA_V0_RIE = BIT(4),
- DW_HDMA_V0_LWIE = BIT(3),
- DW_HDMA_V0_RWIE = BIT(4), DW_HDMA_V0_CCS = BIT(8), DW_HDMA_V0_LLE = BIT(9), };
@@ -195,25 +195,14 @@ static void dw_hdma_v0_write_ll_link(struct dw_edma_chunk *chunk, static void dw_hdma_v0_core_write_chunk(struct dw_edma_chunk *chunk) { struct dw_edma_burst *child;
- struct dw_edma_chan *chan = chunk->chan; u32 control = 0, i = 0;
- int j; if (chunk->cb) control = DW_HDMA_V0_CB;
- j = chunk->bursts_alloc;
- list_for_each_entry(child, &chunk->burst->list, list) {
j--;if (!j) {control |= DW_HDMA_V0_LIE;if (!(chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL))control |= DW_HDMA_V0_RIE;}
- list_for_each_entry(child, &chunk->burst->list, list) dw_hdma_v0_write_ll_data(chunk, i++, control, child->sz, child->sar, child->dar);
- }
Hm, in case of DW EDMA the LIE/RIE flags of the LL entries gets to be moved to the LIE/RIE flags of the channel context register by the DMA-engine. In its turn the context register LIE/RIE flags determine whether the Local and Remote Done/Abort IRQs being raised. So without the LIE/RIE flags being set in the LL-entries the IRQs won't be raised and the whole procedure won't work. I have doubts it works differently in case of HDMA because changing the semantics would cause implementing additional logic in the DW HDMA RTL-model. Seeing the DW HDMA IP-core supports the eDMA compatibility mode it would needlessly expand the controller size. What are the rest of the CONTROL1 register fields? There must be LIE/RIE flags someplace there for the non-LL transfers and to preserve the values retrieved from the LL-entries.
Moreover the DW eDMA HW manual has a dedicated chapter called "Interrupts and Error Handling" with a very demonstrative figures describing the way the flags work. Does the DW HDMA databook have something like that?
Please also note, the DW _EDMA_ LIE and RIE flags can be also utilized for the intermediate IRQ raising, to implement the runtime LL-entries recycling pattern. The IRQ in that case is called as "watermark" IRQ in the DW EDMA HW databook, but the flags are still called as just LIE/RIE.
-Serge(y)
Yes, you are right LIE/RIE flags need to be set without that the IRQs won't be raised in case of DW EDMA. But in DW HDMA case there in no such LIE/RIE flags and these particular bits has been mapped to LWIE and RWIE flags and these are used to enable watermark interrupt only. There is no LIE/RIE fields in HDMA_CONTROL1_OFF_WRCH register fields the same is present in EDMA CONTROL1 register.
DW HDMA has INT_SETUP register and it has LSIE/RSIE, LAIE/RAIE fields those are enabling Local and Remote Stop/Abort IRQs in LL mode.
yes DW HDMA data book also have figures in "Interrupts and Error Handling" section and there is no LIE/RIE flags and it is replaced with LWIE/RWIE flags as I mentioned above.
Got it. Thanks for clarification. No more notes in this regard. Reviewed-by: Serge Semin fancer.lancer@gmail.com
-Serge(y)
Thanks, Mrinmay
control = DW_HDMA_V0_LLP | DW_HDMA_V0_TCB; if (!chunk->cb) -- 2.7.4