On Fri, Sep 18, 2020 at 11:42:54AM +0800, Reddy, MallikarjunaX wrote:
> On 9/9/2020 7:14 PM, Andy Shevchenko wrote:
> > On Wed, Sep 09, 2020 at 07:07:34AM +0800, Amireddy Mallikarjuna reddy wrote:
...
> > > + help
> > > + Enable support for intel Lightning Mountain SOC DMA controllers.
> > > + These controllers provide DMA capabilities for a variety of on-chip
> > > + devices such as SSC, HSNAND and GSWIP.
> > And how module will be called?
> ?are you expecting to include 'default y' ?
I'm expecting to see something like "if you choose M the module will be called
bla-foo-bar." Look at the existing examples in the kernel.
...
> > > +ldma_update_bits(struct ldma_dev *d, u32 mask, u32 val, u32 ofs)
> > > +{
> > > + u32 old_val, new_val;
> > > +
> > > + old_val = readl(d->base + ofs);
> > > + new_val = (old_val & ~mask) | (val & mask);
> > With bitfield.h you will have this as u32_replace_bits().
> -? new_val = (old_val & ~mask) | (val & mask);
> + new_val = old_val;
> + u32_replace_bits(new_val, val, mask);
>
> I think in this function we cant use this because of compilation issues
> thrown by bitfield.h . Expecting 2nd and 3rd arguments as constant numbers
> not as type variables.
>
> ex:
> u32_replace_bits(val, 0, IPA_REG_ENDP_ROUTER_HASH_MSK_ALL);
How comes these are constants? In the above you have a function which does
r-m-w approach to the register. It should be something like
old = read();
new = u32_replace_bits(old, ...);
write(new);
> ./include/linux/bitfield.h:131:3: error: call to '__field_overflow' declared
> with attribute error: value doesn't fit into mask
> ?? __field_overflow();???? \
> ?? ^~~~~~~~~~~~~~~~~~
>
> ./include/linux/bitfield.h:119:3: error: call to '__bad_mask' declared with
> attribute error: bad bitfield mask
> ?? __bad_mask();
> ?? ^~~~~~~~~~~~
So, even with constants u32_replace_bits() must work. Maybe you didn't get how?
> > > + if (new_val != old_val)
> > > + writel(new_val, d->base + ofs);
> > > +}
...
> > > + /* High 4 bits */
> > Why only 4?
> this is higher 4 bits of 36 bit addressing..
Make it clear in the comment.
...
> > > +device_initcall(intel_ldma_init);
> > Each _initcall() in general should be explained.
> ok. is it fine?
>
> /* Perform this driver as device_initcall to make sure initialization
> happens
> ?* before its dma clients of some are platform specific. make sure to
> provice
> ?* registered dma channels and dma capabilities to client before their
> ?* initialization.
> ?*/
/*
* Just follow proper multi-line comment style.
* And use dma -> DMA.
*/
--
With Best Regards,
Andy Shevchenko
Hi Andy,
Thanks for your comments. My comments are in line.
On 9/18/2020 8:20 PM, Andy Shevchenko wrote:
> On Fri, Sep 18, 2020 at 11:42:54AM +0800, Reddy, MallikarjunaX wrote:
>> On 9/9/2020 7:14 PM, Andy Shevchenko wrote:
>>> On Wed, Sep 09, 2020 at 07:07:34AM +0800, Amireddy Mallikarjuna reddy wrote:
> ...
>
>>>> + help
>>>> + Enable support for intel Lightning Mountain SOC DMA controllers.
>>>> + These controllers provide DMA capabilities for a variety of on-chip
>>>> + devices such as SSC, HSNAND and GSWIP.
>>> And how module will be called?
>> are you expecting to include 'default y' ?
> I'm expecting to see something like "if you choose M the module will be called
> bla-foo-bar." Look at the existing examples in the kernel.
ok, i will change bool to tristate.
>
> ...
>
>>>> +ldma_update_bits(struct ldma_dev *d, u32 mask, u32 val, u32 ofs)
>>>> +{
>>>> + u32 old_val, new_val;
>>>> +
>>>> + old_val = readl(d->base + ofs);
>>>> + new_val = (old_val & ~mask) | (val & mask);
>>> With bitfield.h you will have this as u32_replace_bits().
>> - new_val = (old_val & ~mask) | (val & mask);
>> + new_val = old_val;
>> + u32_replace_bits(new_val, val, mask);
>>
>> I think in this function we cant use this because of compilation issues
>> thrown by bitfield.h . Expecting 2nd and 3rd arguments as constant numbers
>> not as type variables.
>>
>> ex:
>> u32_replace_bits(val, 0, IPA_REG_ENDP_ROUTER_HASH_MSK_ALL);
> How comes these are constants? In the above you have a function which does
> r-m-w approach to the register. It should be something like
>
> old = read();
> new = u32_replace_bits(old, ...);
> write(new);
>
>> ./include/linux/bitfield.h:131:3: error: call to '__field_overflow' declared
>> with attribute error: value doesn't fit into mask
>> __field_overflow(); \
>> ^~~~~~~~~~~~~~~~~~
>>
>> ./include/linux/bitfield.h:119:3: error: call to '__bad_mask' declared with
>> attribute error: bad bitfield mask
>> __bad_mask();
>> ^~~~~~~~~~~~
> So, even with constants u32_replace_bits() must work. Maybe you didn't get how?
Thanks Andy, now i know how u32_replace_bits() is working.
The mask is not the continuous bits in some cases. Due to the mask bits
are not continuous u32_replace_bits() can't be used here.
Ex:
u32 mask = DMA_CPOLL_EN | DMA_CPOLL_CNT;
Comes to __field_overflow error, update bits in the 'val' are aligned
with mask bits. Because of the this reason in u32_replace_bits() 'val'
exceeds the 'mask' in some cases which is causing __field_overflow error.
>>>> + if (new_val != old_val)
>>>> + writel(new_val, d->base + ofs);
>>>> +}
> ...
>
>>>> + /* High 4 bits */
>>> Why only 4?
>> this is higher 4 bits of 36 bit addressing..
> Make it clear in the comment.
ok.
>
> ...
>
>>>> +device_initcall(intel_ldma_init);
>>> Each _initcall() in general should be explained.
>> ok. is it fine?
>>
>> /* Perform this driver as device_initcall to make sure initialization
>> happens
>> * before its dma clients of some are platform specific. make sure to
>> provice
>> * registered dma channels and dma capabilities to client before their
>> * initialization.
>> */
> /*
> * Just follow proper multi-line comment style.
> * And use dma -> DMA.
> */
Ok.