dmaengine: dw-edma: Fix multiple times setting of the CYCLE_STATE and CYCLE_BIT bits for HDMA.

Others have submitted this issue (https://lore.kernel.org/dmaengine/
20240722030405.3385-1-zhengdongxiong@gxmicro.cn/),
but it has not been fixed yet. Therefore, more supplementary information
is provided here.

As mentioned in the "PCS-CCS-CB-TCB" Producer-Consumer Synchronization of
"DesignWare Cores PCI Express Controller Databook, version 6.00a":

1. The Consumer CYCLE_STATE (CCS) bit in the register only needs to be
initialized once; the value will update automatically to be
~CYCLE_BIT (CB) in the next chunk.
2. The Consumer CYCLE_BIT bit in the register is loaded from the LL
element and tested against CCS. When CB = CCS, the data transfer is
executed. Otherwise not.

The current logic sets customer (HDMA) CS and CB bits to 1 in each chunk
while setting the producer (software) CB of odd chunks to 0 and even
chunks to 1 in the linked list. This is leading to a mismatch between
the producer CB and consumer CS bits.

This issue can be reproduced by setting the transmission data size to
exceed one chunk. By the way, in the EDMA using the same "PCS-CCS-CB-TCB"
mechanism, the CS bit is only initialized once and this issue was not
found. Refer to
drivers/dma/dw-edma/dw-edma-v0-core.c:dw_edma_v0_core_start.

So fix this issue by initializing the CYCLE_STATE and CYCLE_BIT bits
only once.

Fixes: e74c39573d35 ("dmaengine: dw-edma: Add support for native HDMA")
Signed-off-by: LUO Haowen <luo-hw@foxmail.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/tencent_CB11AA9F3920C1911AF7477A9BD8EFE0AD05@qq.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

0 files changed, 0 insertions, 0 deletions