linux-kernel - Re: [PATCH v7 2/2] drivers: soc: Add LLCC driver

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Date:   Tue, 22 May 2018 13:40:49 -0700
From:   rishabhb@...eaurora.org
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        linux-arm-msm@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm@...ts.infradead.org, tsoni@...eaurora.org,
        ckadabi@...eaurora.org, Evan Green <evgreen@...omium.org>,
        Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v7 2/2] drivers: soc: Add LLCC driver

On 2018-05-22 12:38, Andy Shevchenko wrote:
> On Tue, May 22, 2018 at 9:33 PM,  <rishabhb@...eaurora.org> wrote:
>> On 2018-05-18 14:01, Andy Shevchenko wrote:
>>> On Wed, May 16, 2018 at 8:43 PM, Rishabh Bhatnagar
>>> <rishabhb@...eaurora.org> wrote:
> 
>>>> +#define ACTIVATE                      0x1
>>>> +#define DEACTIVATE                    0x2
>>>> +#define ACT_CTRL_OPCODE_ACTIVATE      0x1
>>>> +#define ACT_CTRL_OPCODE_DEACTIVATE    0x2
>>>> +#define ACT_CTRL_ACT_TRIG             0x1
>>> 
>>> 
>>> Are these bits? Perhaps BIT() ?
>>> 
>> isn't it just better to use fixed size as u suggest in the next 
>> comment?
> 
> If the are bits, use BIT() macro.
> 
>>>> +struct llcc_slice_desc *llcc_slice_getd(u32 uid)
>>>> +{
>>>> +       const struct llcc_slice_config *cfg;
>>>> +       struct llcc_slice_desc *desc;
>>>> +       u32 sz, count = 0;
>>>> +
>>>> +       cfg = drv_data->cfg;
>>>> +       sz = drv_data->cfg_size;
>>>> +
>>> 
>>> 
>>>> +       while (cfg && count < sz) {
>>>> +               if (cfg->usecase_id == uid)
>>>> +                       break;
>>>> +               cfg++;
>>>> +               count++;
>>>> +       }
>>>> +       if (cfg == NULL || count == sz)
>>>> +               return ERR_PTR(-ENODEV);
>>> 
>>> 
>>> if (!cfg)
>>>           return ERR_PTR(-ENODEV);
>>> 
>>> while (cfg->... != uid) {
>>>   cfg++;
>>>   count++;
>>> }
>>> 
>>> if (count == sz)
>>>  return ...
>>> 
>>> Though I would rather put it to for () loop.
>>> 
>> In each while loop iteration the cfg pointer needs to be checked for
>> NULL. What if the usecase id never matches the uid passed by client
>> and we keep iterating. At some point it will crash.
> 
> do {
>   if (!cfg || count == sz)
>    return ...(-ENODEV);
>  ...
> } while (...);
> 
> Though, as I said for-loop will look slightly better I think.
Is this fine?
for (count = 0; count < sz; count++) {
    if (!cfg)
	return ERR_PTR(-ENODEV);
    if (cfg->usecase_id == uid)
	break;
    cfg++;
}
if (count == sz)
    return ERR_PTR(-ENODEV);

> 
>>>> +       ret = llcc_update_act_ctrl(desc->slice_id, act_ctrl_val,
>>>> +                                 DEACTIVATE);
>>> 
>>> 
>>> Perhaps one line (~83 characters here is OK) ?
>> 
>> The checkpatch script complains about such lines.
> 
> So what if it just 3 characters out?
> 
Other reviewers sometimes are not okay if the checkpatch complains.
Because I have gotten many reviews previously concerning about line
length. Not sure how to proceed here.

>>>> +       ret = llcc_update_act_ctrl(desc->slice_id, act_ctrl_val,
>>>> +                                 ACTIVATE);
> 
>>> Ditto.
> 
>>>> +               attr1_cfg = bcast_off +
>>>> +
>>>> LLCC_TRP_ATTR1_CFGn(llcc_table[i].slice_id);
>>>> +               attr0_cfg = bcast_off +
>>>> +
>>>> LLCC_TRP_ATTR0_CFGn(llcc_table[i].slice_id);
> 
>>> Ditto.
> 
>>>> +               attr1_val |= llcc_table[i].probe_target_ways <<
>>>> +                               ATTR1_PROBE_TARGET_WAYS_SHIFT;
>>>> +               attr1_val |= llcc_table[i].fixed_size <<
>>>> +                               ATTR1_FIXED_SIZE_SHIFT;
>>>> +               attr1_val |= llcc_table[i].priority <<
>>>> ATTR1_PRIORITY_SHIFT;
> 
>>> foo |=
>>>   bar << SHIFT;
>>> 
>>> would look slightly better.
> 
> Did you consider this option ?
Yes, forgot to mention.