Thread (4 messages) 4 messages, 3 authors, 2018-11-30

Re: [PATCH] usb: chipidea: imx: unify over-current polarity handling

From: Uwe Kleine-König <hidden>
Date: 2018-11-30 21:35:29
Also in: linux-usb

Hello Fabio,

On Fri, Nov 30, 2018 at 07:16:39PM -0200, Fabio Estevam wrote:
[Adding Matt]

On Fri, Nov 30, 2018 at 6:53 PM Uwe Kleine-König
[off-list ref] wrote:
quoted
The status quo is:
 - on i.MX25 the overcurrent polarity is always explicitly configured as
   active high which matches the reset default.
 - on i.MX6 and i.MX7 the overcurrent polarity is active high after
   reset. usbmisc_imx6q_init() and usbmisc_imx7d_init() keep the current
   state (probably as setup by the bootloader or still the reset
   default) unless the polarity is explicitly configured as active high
   which then is configured. (So if the pin is active low and the
   bootloader didn't set this up the configuration is wrong.)

To improve the situation always configure the reset default value unless
the device tree configures the polarity (and then use this one).

Note that as the reset default is active high on all platforms there is
no need to check for the presence of "over-current-active-high". In the
absence of "over-current-active-low" it doesn't matter if active high is
configured because that's the default or because it is configured
explicitly.

Signed-off-by: Uwe Kleine-König <redacted>
It seems that Matt is also interested in adding the
'over-current-active-low' property:
https://patchwork.kernel.org/patch/10701311/
Looking at Matt's patch I noticed that I applied my patch on an old
kernel version (4.14) :-|

But I think Matt's patch is broken because in usbmisc_imx6q_init() in
the last else branch MX6_BM_OVER_CUR_POLARITY isn't cleared. Other than
that they don't look that different semantically.

I will respin my patch on Monday.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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