Subject: [PATCH 1/3] ARM: OMAP: hwmod: partially un-reset hwmods might not be properly enabled

From: [email-masked] (Benoit Cousson)
Date: Mon, 20 Aug 2012 16:49:40 +0200

Hi Omar,

On 07/16/2012 09:21 PM, Omar Ramirez Luna wrote:
> Some IP blocks might not be using/controlling more than one
> reset line, this check loosens the restriction to fully use
> hwmod framework for those drivers.
> 
> E.g.: ipu has reset lines: mmu_cache, cpu0 and cpu1.
> - cpu1 might not be used and hence (with previous check)
>   won't be fully enabled by hwmod code.

You mean that you might have some case where you need to enable the
mmu_cache and cpu0 and thus deassert only the mmu/cpu0 while keeping the
cpu1 under reset?

So the any_hardreset is indeed not appropriate in that case.

In fact, since the hardreset cannot be handled at all by the hwmod fmwk,
I'm even wondering if we should take care of checking the state at all.
But as Paul stated, if was done due to the lack of understanding about
the diver usage, so maybe things will become clearer once we will have
that code available.

So I guess that checking for all the lines for the hardreset state is
anyway already a first step toward a good understanding of the reset
need for the remote processors.

The patch looks fine to me considering that we do not have a lot of
information about the usage :-(

Maybe you could add more information in the changelog to explain the way
you are going to use the reset API.

Regards,
Benoit

> While at it, prevent _omap4_module_disable if all the hardreset
> lines on an IP block are not under reset.

> 
> Signed-off-by: Omar Ramirez Luna <[email-masked]>
> ---
>  arch/arm/mach-omap2/omap_hwmod.c |   37 ++++++++++++++++++++++---------------
>  1 files changed, 22 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
> index 3215dad..091c199 100644
> --- a/arch/arm/mach-omap2/omap_hwmod.c
> +++ b/arch/arm/mach-omap2/omap_hwmod.c
> @@ -1558,25 +1558,28 @@ static int _read_hardreset(struct omap_hwmod *oh, const char *name)
>  }
>  
>  /**
> - * _are_any_hardreset_lines_asserted - return true if part of @oh is hard-reset
> + * _are_all_hardreset_lines_asserted - return true if the @oh is hard-reset
>   * @oh: struct omap_hwmod *
>   *
> - * If any hardreset line associated with @oh is asserted, then return true.
> - * Otherwise, if @oh has no hardreset lines associated with it, or if
> - * no hardreset lines associated with @oh are asserted, then return false.
> + * If all hardreset lines associated with @oh are asserted, then return true.
> + * Otherwise, if part of @oh is out hardreset or if no hardreset lines
> + * associated with @oh are asserted, then return false.
>   * This function is used to avoid executing some parts of the IP block
> - * enable/disable sequence if a hardreset line is set.
> + * enable/disable sequence if its hardreset line is set.
>   */
> -static bool _are_any_hardreset_lines_asserted(struct omap_hwmod *oh)
> +static bool _are_all_hardreset_lines_asserted(struct omap_hwmod *oh)
>  {
> -	int i;
> +	int i, rst_cnt = 0;
>  
>  	if (oh->rst_lines_cnt == 0)
>  		return false;
>  
>  	for (i = 0; i < oh->rst_lines_cnt; i++)
>  		if (_read_hardreset(oh, oh->rst_lines[i].name) > 0)
> -			return true;
> +			rst_cnt++;
> +
> +	if (oh->rst_lines_cnt == rst_cnt)
> +		return true;
>  
>  	return false;
>  }
> @@ -1595,6 +1598,13 @@ static int _omap4_disable_module(struct omap_hwmod *oh)
>  	if (!oh->clkdm || !oh->prcm.omap4.modulemode)
>  		return -EINVAL;
>  
> +	/*
> +	 * Since integration code might still be doing something, only
> +	 * disable if all lines are under hardreset.
> +	 */
> +	if (!_are_all_hardreset_lines_asserted(oh))
> +		return 0;
> +
>  	pr_debug("omap_hwmod: %s: %s\n", oh->name, __func__);
>  
>  	omap4_cminst_module_disable(oh->clkdm->prcm_partition,
> @@ -1602,9 +1612,6 @@ static int _omap4_disable_module(struct omap_hwmod *oh)
>  				    oh->clkdm->clkdm_offs,
>  				    oh->prcm.omap4.clkctrl_offs);
>  
> -	if (_are_any_hardreset_lines_asserted(oh))
> -		return 0;
> -
>  	v = _omap4_wait_target_disable(oh);
>  	if (v)
>  		pr_warn("omap_hwmod: %s: _wait_target_disable failed\n",
> @@ -1830,7 +1837,7 @@ static int _enable(struct omap_hwmod *oh)
>  	}
>  
>  	/*
> -	 * If an IP block contains HW reset lines and any of them are
> +	 * If an IP block contains HW reset lines and all of them are
>  	 * asserted, we let integration code associated with that
>  	 * block handle the enable.  We've received very little
>  	 * information on what those driver authors need, and until
> @@ -1838,7 +1845,7 @@ static int _enable(struct omap_hwmod *oh)
>  	 * posted to the public lists, this is probably the best we
>  	 * can do.
>  	 */
> -	if (_are_any_hardreset_lines_asserted(oh))
> +	if (_are_all_hardreset_lines_asserted(oh))
>  		return 0;
>  
>  	/* Mux pins for device runtime if populated */
> @@ -1918,7 +1925,7 @@ static int _idle(struct omap_hwmod *oh)
>  		return -EINVAL;
>  	}
>  
> -	if (_are_any_hardreset_lines_asserted(oh))
> +	if (_are_all_hardreset_lines_asserted(oh))
>  		return 0;
>  
>  	if (oh->class->sysc)
> @@ -2006,7 +2013,7 @@ static int _shutdown(struct omap_hwmod *oh)
>  		return -EINVAL;
>  	}
>  
> -	if (_are_any_hardreset_lines_asserted(oh))
> +	if (_are_all_hardreset_lines_asserted(oh))
>  		return 0;
>  
>  	pr_debug("omap_hwmod: %s: disabling\n", oh->name);
>