Re: [PATCH] dma: ti: k3-udma: Workaround errata i2234

Hello Peter,

On 10/12/21 20:52, Péter Ujfalusi wrote:

Hi Vignesh,

On 09/12/2021 20:07, Vignesh Raghavendra wrote:

quoted

Per [1], UDMA TR15 transactions may hang if ICNT0 is less than 64B
Work around is to set EOL flag is to 1 for ICNT0.

Since, there is no performance penalty / side effects of setting EOL
flag event ICNTO > 64B, just set the flag for all UDMAP TR15
descriptors.

PDMAs and CSI does not send EOL? If you set it the EOL to one then when
it arrives the remaining icnt0 is skipped...

I am planning to respin v2 for this.
Will fix this in v2.

quoted

[1] https://www.ti.com/lit/er/sprz455a/sprz455a.pdf
Errata doc for J721E DRA829/TDA4VM Processors Silicon Revision 1.1/1.0 (Rev. A)

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
---
  drivers/dma/ti/k3-udma.c     | 48 +++++++++++++++++++-----------------
  include/linux/dma/ti-cppi5.h |  1 +
  2 files changed, 27 insertions(+), 22 deletions(-)

[...]

quoted

diff --git a/include/linux/dma/ti-cppi5.h b/include/linux/dma/ti-cppi5.h
index efa2f0309f00..c53c0f6e3b1a 100644
--- a/include/linux/dma/ti-cppi5.h
+++ b/include/linux/dma/ti-cppi5.h

@@ -616,6 +616,7 @@ static inline void *cppi5_hdesc_get_swdata(struct cppi5_host_desc_t *desc)
  #define   CPPI5_TR_CSF_SUPR_EVT			BIT(2)
  #define   CPPI5_TR_CSF_EOL_ADV_SHIFT		(4U)
  #define   CPPI5_TR_CSF_EOL_ADV_MASK		GENMASK(6, 4)
+#define   CPPI5_TR_CSF_EOL_ICNT0		BIT(4)

the correct expression is: (1 << CPPI5_TR_CSF_EOL_ADV_SHIFT)

Both these expressions expands to the same value
(CPPI5_TR_CSF_EOL_ADV_SHIFT = 4U)

And according to the linux checkpatch, the usage of BIT macro
is preferred so I will keep it the same.

Warm regards,
-Jayesh

as EOL = 1 is what you want to set.
EOL = 2 will clear icnt0 and 1 on EOL.
3 will do the same for icnt 0, 1 and 2
4 will skip the remainin tr.

quoted

  #define   CPPI5_TR_CSF_EOP			BIT(7)
  
  /**

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