Subject: [PATCH] ARM: OMAP2+: hwmod: Fix _wait_target_ready() for hwmods without sysc

From: [email-masked] (Suman Anna)
Date: Tue, 6 Jan 2015 11:14:40 -0600

Hi Paul,

On 01/06/2015 02:14 AM, Lokesh Vutla wrote:
> Hi Paul,
> On Tuesday 06 January 2015 07:34 AM, Paul Walmsley wrote:
>>
>> Roger, Lokesh, could you try this one instead?
> Yep, the below patch works on AM437x.
> Boot logs here: http://paste.ubuntu.com/9680938/
> 
> Thanks and regards,
> Lokesh
>>
>> It passes all the basic tests here except it does not boot on the 4460 
>> VAR-SOM-OM - unclear why at this point - but it would be good to see if it 
>> works on your AM4372 boards, since I don't have that one.
>>
>> Test logs are here:
>>
>> http://www.pwsan.com/omap/testlogs/hwmod_skip_only_remap_v3.19-rc/20150105171744/
>>
>>
>> - Paul
>>
>>
>> From 4f2e13bd2181e0ebede3aabc484aa2339830748a Mon Sep 17 00:00:00 2001
>> From: Paul Walmsley <[email-masked]>
>> Date: Mon, 5 Jan 2015 15:49:57 -0700
>> Subject: [PATCH] Only skip ioremap() if IP block does not have OCP header
>>  registers. Experimental.
>>
>> ---
>>  arch/arm/mach-omap2/omap_hwmod.c | 33 +++++++++++++++++++++------------
>>  1 file changed, 21 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
>> index cbb908dc5cf0..03df8833d399 100644
>> --- a/arch/arm/mach-omap2/omap_hwmod.c
>> +++ b/arch/arm/mach-omap2/omap_hwmod.c
>> @@ -1938,6 +1938,8 @@ static int _reset(struct omap_hwmod *oh)
>>  	pr_debug("omap_hwmod: %s: resetting\n", oh->name);
>>  
>>  	if (oh->class->reset) {
>> +		WARN(!oh->_mpu_rt_va, "Attempt to call custom reset with no MPU register target ioremapped: %s",
>> +		     oh->name);
>>  		r = oh->class->reset(oh);
>>  	} else {
>>  		if (oh->rst_lines_cnt > 0) {
>> @@ -2358,15 +2360,19 @@ static int of_dev_hwmod_lookup(struct device_node *np,
>>  }
>>  
>>  /**
>> - * _init_mpu_rt_base - populate the virtual address for a hwmod
>> + * _init_mpu_rt_base - populate the MPU port and virtual address
>>   * @oh: struct omap_hwmod * to locate the virtual address
>>   * @data: (unused, caller should pass NULL)
>>   * @index: index of the reg entry iospace in device tree
>>   * @np: struct device_node * of the IP block's device node in the DT data
>>   *
>> - * Cache the virtual address used by the MPU to access this IP block's
>> - * registers.  This address is needed early so the OCP registers that
>> - * are part of the device's address space can be ioremapped properly.
>> + * Cache the interconnect target port and the virtual address used by
>> + * the MPU to access this IP block's registers.  The address is needed
>> + * early so the OCP registers that are part of the device's address
>> + * space can be ioremapped properly.  The presence or absence of the
>> + * interconnect target port also indicates whether the hwmod code
>> + * should wait for the IP block to indicate readiness after it is
>> + * enabled.
>>   *
>>   * Returns 0 on success, -EINVAL if an invalid hwmod is passed, and
>>   * -ENXIO on absent or invalid register target address space.
>> @@ -2385,6 +2391,13 @@ static int __init _init_mpu_rt_base(struct omap_hwmod *oh, void *data,
>>  	if (oh->_int_flags & _HWMOD_NO_MPU_PORT)
>>  		return -ENXIO;
>>  
>> +	/*
>> +	 * If there's no need for the hwmod code to read or write to
>> +	 * the IP block registers, bail out early before the ioremap()
>> +	 */
>> +	if (!oh->class->sysc)
>> +		return 0;
>> +
>>  	mem = _find_mpu_rt_addr_space(oh);
>>  	if (!mem) {
>>  		pr_debug("omap_hwmod: %s: no MPU register target found\n",
>> @@ -2451,14 +2464,10 @@ static int __init _init(struct omap_hwmod *oh, void *data)
>>  				oh->name, np->name);
>>  	}
>>  
>> -	if (oh->class->sysc) {
>> -		r = _init_mpu_rt_base(oh, NULL, index, np);
>> -		if (r < 0) {
>> -			WARN(1, "omap_hwmod: %s: doesn't have mpu register target base\n",
>> -			     oh->name);
>> -			return 0;
>> -		}
>> -	}
>> +	r = _init_mpu_rt_base(oh, NULL, index, np);
>> +	if (r < 0)
>> +		pr_debug("omap_hwmod: %s: doesn't have mpu register target base\n",
>> +			 oh->name);

You have removed the return from the above block on failure. If any DT
entry doesn't have the reg property, this will hang the kernel boot.
Just remove the "reg" entry from any of the existing DT, and you will
run into the issue, this is what 6423d6df1440 ("ARM: OMAP2+: hwmod:
check for module address space during init") fixed. Also, are you sure
you want to turn the WARN into a pr_debug, it won't even show during the
kernel boot log if the reg base is missing.

regards
Suman

>>  
>>  	r = _init_clocks(oh, NULL);
>>  	if (r < 0) {
>>
>