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[0/4] i2c: rcar: handle Gen2 and Gen3 V3U quirks better

Message ID 20201223172154.34462-1-wsa+renesas@sang-engineering.com
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Series i2c: rcar: handle Gen2 and Gen3 V3U quirks better | expand

Message

Wolfram Sang Dec. 23, 2020, 5:21 p.m. UTC
The new V3U SoC needs handling of spurious interrupts which is handled
in patch #4. However, this extra check is bad for Gen2 and earlier SoCs,
so we need seperate interrupts now. While working on this, further
improvements to avoid the HW race condition on Gen2 and earlier have
been found, see patches 1-3.

My measurements have shown that patches 1+2 really improve the
situation. Before, I could see doubled messages after adding 2us of
delay to the interrupt handler. After, they only started to appear after
7us. I can't say much about the spurious interrupts on V3U. The BSP team
experienced them, I did not so far.

Let me know what you think...


Wolfram Sang (4):
  i2c: rcar: faster irq code to minimize HW race condition
  i2c: rcar: optimize cacheline to minimize HW race condition
  i2c: rcar: make sure irq is not threaded on Gen2 and earlier
  i2c: rcar: protect against supurious interrupts on V3U

 drivers/i2c/busses/i2c-rcar.c | 66 +++++++++++++++++++++++++----------
 1 file changed, 48 insertions(+), 18 deletions(-)

Comments

Niklas Söderlund Dec. 27, 2020, 2:20 p.m. UTC | #1
Hi Wolfram,

Thanks for your series.

On 2020-12-23 18:21:50 +0100, Wolfram Sang wrote:
> The new V3U SoC needs handling of spurious interrupts which is handled

> in patch #4. However, this extra check is bad for Gen2 and earlier SoCs,

> so we need seperate interrupts now. While working on this, further

> improvements to avoid the HW race condition on Gen2 and earlier have

> been found, see patches 1-3.

> 

> My measurements have shown that patches 1+2 really improve the

> situation. Before, I could see doubled messages after adding 2us of

> delay to the interrupt handler. After, they only started to appear after

> 7us. I can't say much about the spurious interrupts on V3U. The BSP team

> experienced them, I did not so far.

> 

> Let me know what you think...


I like it, for the whole series

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>


> 

> 

> Wolfram Sang (4):

>   i2c: rcar: faster irq code to minimize HW race condition

>   i2c: rcar: optimize cacheline to minimize HW race condition

>   i2c: rcar: make sure irq is not threaded on Gen2 and earlier

>   i2c: rcar: protect against supurious interrupts on V3U

> 

>  drivers/i2c/busses/i2c-rcar.c | 66 +++++++++++++++++++++++++----------

>  1 file changed, 48 insertions(+), 18 deletions(-)

> 

> -- 

> 2.28.0

> 


-- 
Regards,
Niklas Söderlund