linux-kernel - Re: [PATCH] mfd: omap-usb-tll: Fix inverted bit use for USB TLL mode

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Date:   Tue, 11 Apr 2017 10:28:52 +0300
From:   Roger Quadros <rogerq@...com>
To:     Tony Lindgren <tony@...mide.com>, Lee Jones <lee.jones@...aro.org>,
        Samuel Ortiz <sameo@...ux.intel.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Marcel Partap <mpartap@....net>,
        Michael Scott <michael.scott@...aro.org>,
        Sebastian Reichel <sre@...nel.org>
Subject: Re: [PATCH] mfd: omap-usb-tll: Fix inverted bit use for USB TLL mode

Hi Tony,

On 11/04/17 03:15, Tony Lindgren wrote:
> Commit 16fa3dc75c22 ("mfd: omap-usb-tll: HOST TLL platform driver")
> added support for USB TLL, but uses OMAP_TLL_CHANNEL_CONF_ULPINOBITSTUFF
> bit the wrong way. The comments in the code are mostly correct, but the
> inverted use of OMAP_TLL_CHANNEL_CONF_ULPINOBITSTUFF causes the register
> to be enabled instead of disabled like the comments say. And the
> idle mode should be only disabled for UTMIAUTOIDLE while ULPIAUTOIDLE
> can be enabled.
> 
> This matches the TLL_CHANNEL_CONF_i register configuration for ehci-tll
> in the Motorola Linux kernel tree for Wrigley 3G LTE modem on droid 4.
> Without this patch the modem can only be pinged few times before it
> stops responding. Also lsub -v output shows errors without this patch.

This patch does 2 things.
- Fixes the bad commit by correctly disabling Bitstuffing
- Enables ULPI Autoidle.

Is enabling ULPI autoidle required to fix the LTE modem issue? If not I'd put it
in a separate patch.

cheers,
-roger

> 
> Fixes: 16fa3dc75c22 ("mfd: omap-usb-tll: HOST TLL platform driver")
> Cc: Felipe Balbi <felipe.balbi@...ux.intel.com>
> Cc: Keshava Munegowda <keshava_mgowda@...com>
> Cc: Marcel Partap <mpartap@....net>
> Cc: Michael Scott <michael.scott@...aro.org>
> Cc: Roger Quadros <rogerq@...com>
> Cc: Sebastian Reichel <sre@...nel.org>
> Signed-off-by: Tony Lindgren <tony@...mide.com>
> ---
>  drivers/mfd/omap-usb-tll.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
> --- a/drivers/mfd/omap-usb-tll.c
> +++ b/drivers/mfd/omap-usb-tll.c
> @@ -373,12 +373,13 @@ int omap_tll_init(struct usbhs_omap_platform_data *pdata)
>  			} else if (pdata->port_mode[i] ==
>  					OMAP_EHCI_PORT_MODE_TLL) {
>  				/*
> -				 * Disable AutoIdle, BitStuffing
> -				 * and use SDR Mode
> +				 * Disable UTMI AutoIdle, BitStuffing
> +				 * and use SDR Mode. Enable ULPI AutoIdle.
>  				 */
> -				reg &= ~(OMAP_TLL_CHANNEL_CONF_UTMIAUTOIDLE
> -					| OMAP_TLL_CHANNEL_CONF_ULPINOBITSTUFF
> -					| OMAP_TLL_CHANNEL_CONF_ULPIDDRMODE);
> +				reg &= ~(OMAP_TLL_CHANNEL_CONF_UTMIAUTOIDLE |
> +					 OMAP_TLL_CHANNEL_CONF_ULPIDDRMODE);
> +				reg |= OMAP_TLL_CHANNEL_CONF_ULPINOBITSTUFF;
> +				reg |= OMAP_TLL_CHANNEL_CONF_ULPI_ULPIAUTOIDLE;
>  			} else if (pdata->port_mode[i] ==
>  					OMAP_EHCI_PORT_MODE_HSIC) {
>  				/*
>