* MXS i2c PIOQ/DMA mode selection via DT
@ 2012-07-16 14:05 ` Marek Vasut
0 siblings, 0 replies; 4+ messages in thread
From: Marek Vasut @ 2012-07-16 14:05 UTC (permalink / raw)
To: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ
Cc: Shawn Guo, linux-i2c-u79uwXL29TY76Z2rM5mHXA, Detlev Zundel,
Dong Aisheng, Fabio Estevam, Linux ARM kernel, Sascha Hauer,
Stefano Babic, Uwe Kleine-König, Wolfgang Denk, Wolfram Sang
Hello,
There's been this patch going on, which adds DMA mode into MXS i2c driver:
https://patchwork.kernel.org/patch/1174051/
Recent nitpick was about toggling the PIOQUEUE (almost like PIO, only transfer
mode in current implementation) vs. DMA mode (newly added) on a per-bus basis.
Current implementation in the patch adds a DT property, "fsl,use-pio" (shall be
changed to "fsl,use-pioqueue", but that's irrelevant) to select between the
PIOQUEUE and DMA mode on per-bus basis.
There was now a suggestion to dump this property and use kernel module parameter
instead. This obviously disallows to configure this behavior on per-bus basis.
Consider a scenario where small transfers happens on one bus (possibly from a
sensor) and large transfers on the other bus (eg. i2c EEPROM). In such scenario,
it's beneficial to enable PIOQUEUE mode for the sensor and DMA mode for the
EEPROM to minimize the overall overhead.
The mixed mode (PIOQ for small data and DMA for large data transfers) isn't
supported yet.
Please advise.
Best regards,
Marek Vasut
^ permalink raw reply [flat|nested] 4+ messages in thread
* MXS i2c PIOQ/DMA mode selection via DT
@ 2012-07-16 14:05 ` Marek Vasut
0 siblings, 0 replies; 4+ messages in thread
From: Marek Vasut @ 2012-07-16 14:05 UTC (permalink / raw)
To: linux-arm-kernel
Hello,
There's been this patch going on, which adds DMA mode into MXS i2c driver:
https://patchwork.kernel.org/patch/1174051/
Recent nitpick was about toggling the PIOQUEUE (almost like PIO, only transfer
mode in current implementation) vs. DMA mode (newly added) on a per-bus basis.
Current implementation in the patch adds a DT property, "fsl,use-pio" (shall be
changed to "fsl,use-pioqueue", but that's irrelevant) to select between the
PIOQUEUE and DMA mode on per-bus basis.
There was now a suggestion to dump this property and use kernel module parameter
instead. This obviously disallows to configure this behavior on per-bus basis.
Consider a scenario where small transfers happens on one bus (possibly from a
sensor) and large transfers on the other bus (eg. i2c EEPROM). In such scenario,
it's beneficial to enable PIOQUEUE mode for the sensor and DMA mode for the
EEPROM to minimize the overall overhead.
The mixed mode (PIOQ for small data and DMA for large data transfers) isn't
supported yet.
Please advise.
Best regards,
Marek Vasut
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: MXS i2c PIOQ/DMA mode selection via DT
2012-07-16 14:05 ` Marek Vasut
@ 2012-07-18 12:38 ` Marek Vasut
-1 siblings, 0 replies; 4+ messages in thread
From: Marek Vasut @ 2012-07-18 12:38 UTC (permalink / raw)
To: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ
Cc: Shawn Guo, linux-i2c-u79uwXL29TY76Z2rM5mHXA, Detlev Zundel,
Dong Aisheng, Fabio Estevam, Linux ARM kernel, Sascha Hauer,
Stefano Babic, Uwe Kleine-König, Wolfgang Denk, Wolfram Sang
> Hello,
>
> There's been this patch going on, which adds DMA mode into MXS i2c driver:
> https://patchwork.kernel.org/patch/1174051/
>
> Recent nitpick was about toggling the PIOQUEUE (almost like PIO, only
> transfer mode in current implementation) vs. DMA mode (newly added) on a
> per-bus basis.
>
> Current implementation in the patch adds a DT property, "fsl,use-pio"
> (shall be changed to "fsl,use-pioqueue", but that's irrelevant) to select
> between the PIOQUEUE and DMA mode on per-bus basis.
>
> There was now a suggestion to dump this property and use kernel module
> parameter instead. This obviously disallows to configure this behavior on
> per-bus basis. Consider a scenario where small transfers happens on one
> bus (possibly from a sensor) and large transfers on the other bus (eg. i2c
> EEPROM). In such scenario, it's beneficial to enable PIOQUEUE mode for the
> sensor and DMA mode for the EEPROM to minimize the overall overhead.
>
> The mixed mode (PIOQ for small data and DMA for large data transfers) isn't
> supported yet.
>
> Please advise.
>
> Best regards,
> Marek Vasut
BUMP?
^ permalink raw reply [flat|nested] 4+ messages in thread
* MXS i2c PIOQ/DMA mode selection via DT
@ 2012-07-18 12:38 ` Marek Vasut
0 siblings, 0 replies; 4+ messages in thread
From: Marek Vasut @ 2012-07-18 12:38 UTC (permalink / raw)
To: linux-arm-kernel
> Hello,
>
> There's been this patch going on, which adds DMA mode into MXS i2c driver:
> https://patchwork.kernel.org/patch/1174051/
>
> Recent nitpick was about toggling the PIOQUEUE (almost like PIO, only
> transfer mode in current implementation) vs. DMA mode (newly added) on a
> per-bus basis.
>
> Current implementation in the patch adds a DT property, "fsl,use-pio"
> (shall be changed to "fsl,use-pioqueue", but that's irrelevant) to select
> between the PIOQUEUE and DMA mode on per-bus basis.
>
> There was now a suggestion to dump this property and use kernel module
> parameter instead. This obviously disallows to configure this behavior on
> per-bus basis. Consider a scenario where small transfers happens on one
> bus (possibly from a sensor) and large transfers on the other bus (eg. i2c
> EEPROM). In such scenario, it's beneficial to enable PIOQUEUE mode for the
> sensor and DMA mode for the EEPROM to minimize the overall overhead.
>
> The mixed mode (PIOQ for small data and DMA for large data transfers) isn't
> supported yet.
>
> Please advise.
>
> Best regards,
> Marek Vasut
BUMP?
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-07-18 12:38 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2012-07-16 14:05 MXS i2c PIOQ/DMA mode selection via DT Marek Vasut
2012-07-16 14:05 ` Marek Vasut
[not found] ` <201207161605.44379.marek.vasut-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-07-18 12:38 ` Marek Vasut
2012-07-18 12:38 ` Marek Vasut
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