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dmaengine: dw-edma: Prepare LL kicks for event serialization

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Both eDMA and HDMA perform the same remote LL read-back immediately
before writing the doorbell register.

A later patch serializes each raw doorbell write against IRQ event
capture. Keeping the read-back in the provider callback would hold
event_lock across a remote read. Move the common read-back into the
high-level dw_edma_core_ch_doorbell(), where it can run before the
serialized section. Name the provider write wrapper
dw_edma_core_do_ch_doorbell() to distinguish the raw write, and leave
dw_edma_core_ch_maybe_doorbell() to decide whether a kick is needed.

No functional change.

Suggested-by: Frank Li <Frank.li@oss.nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Link: https://patch.msgid.link/20260820173439.2004068-11-den@valinux.co.jp
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Koichiro Den 2026-08-21 02:34:39 +09:00 committed by Vinod Koul
parent 1f59dfa4c3
commit 65d40a9ede
4 changed files with 19 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/dma/dw-edma/dw-edma-core.c
View File

@ -13,6 +13,7 @@
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/dma/edma.h>
#include <linux/dma-mapping.h>
@ -254,6 +255,23 @@ static void dw_edma_finish_termination(struct dw_edma_chan *chan)
chan->status = EDMA_ST_IDLE;
}
static void dw_edma_core_ll_sync(struct dw_edma_chan *chan)
{
/*
* Remote controller registers and LL memory may be reached through
* different paths. Complete posted LL writes before the doorbell.
*/
if (!(chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL))
readl(chan->ll_region.vaddr.io);
}
/* Must be called with vc.lock held for an LL channel. */
static void dw_edma_core_ch_doorbell(struct dw_edma_chan *chan)
{
dw_edma_core_ll_sync(chan);
dw_edma_core_do_ch_doorbell(chan);
}
/* Must be called with vc.lock held. */
static void dw_edma_core_ch_maybe_doorbell(struct dw_edma_chan *chan)
{

2
drivers/dma/dw-edma/dw-edma-core.h
View File

@ -298,7 +298,7 @@ static inline void dw_edma_core_ll_irq_clear(struct dw_edma_chan *chan)
chan->dw->core->ll_irq_clear(chan);
}
static inline void dw_edma_core_ch_doorbell(struct dw_edma_chan *chan)
static inline void dw_edma_core_do_ch_doorbell(struct dw_edma_chan *chan)
{
chan->dw->core->ch_doorbell(chan);
}

16
drivers/dma/dw-edma/dw-edma-v0-core.c
View File

@ -480,20 +480,6 @@ static void dw_edma_v0_core_ch_enable(struct dw_edma_chan *chan)
upper_32_bits(chan->ll_region.paddr));
}
static void dw_edma_v0_sync_ll_data(struct dw_edma_chan *chan)
{
/*
* In case of remote eDMA engine setup, the DW PCIe RP/EP internal
* configuration registers and application memory are normally accessed
* over different buses. Ensure LL-data reaches the memory before the
* doorbell register is toggled by issuing the dummy-read from the remote
* LL memory in a hope that the MRd TLP will return only after the
* last MWr TLP is completed
*/
if (!(chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL))
readl(chan->ll_region.vaddr.io);
}
static void dw_edma_v0_core_ch_config(struct dw_edma_chan *chan)
{
struct dw_edma *dw = chan->dw;
@ -624,8 +610,6 @@ static void dw_edma_v0_core_ch_doorbell(struct dw_edma_chan *chan)
{
struct dw_edma *dw = chan->dw;
dw_edma_v0_sync_ll_data(chan);
/* Doorbell */
SET_RW_32(dw, chan->dir, doorbell,
FIELD_PREP(EDMA_V0_DOORBELL_CH_MASK, chan->id));

16
drivers/dma/dw-edma/dw-hdma-v0-core.c
View File

@ -282,20 +282,6 @@ static void dw_hdma_v0_core_ch_enable(struct dw_edma_chan *chan)
HDMA_V0_CONSUMER_CYCLE_STAT | HDMA_V0_CONSUMER_CYCLE_BIT);
}
static void dw_hdma_v0_sync_ll_data(struct dw_edma_chan *chan)
{
/*
* In case of remote HDMA engine setup, the DW PCIe RP/EP internal
* configuration registers and application memory are normally accessed
* over different buses. Ensure LL-data reaches the memory before the
* doorbell register is toggled by issuing the dummy-read from the remote
* LL memory in a hope that the MRd TLP will return only after the
* last MWr TLP is completed
*/
if (!(chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL))
readl(chan->ll_region.vaddr.io);
}
static void dw_hdma_v0_core_non_ll_start(struct dw_edma_chan *chan,
struct dw_edma_burst *child)
{
@ -393,8 +379,6 @@ static void dw_hdma_v0_core_ch_doorbell(struct dw_edma_chan *chan)
{
struct dw_edma *dw = chan->dw;
dw_hdma_v0_sync_ll_data(chan);
/* Doorbell */
SET_CH_32(dw, chan->dir, chan->id, doorbell, HDMA_V0_DOORBELL_START);
}