Messages in this thread | | | Date | Fri, 18 Sep 2020 15:20:29 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH v6 2/2] Add Intel LGM soc DMA support. |
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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:
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> > > + 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.
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> > > +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); > > > +}
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> > > + /* High 4 bits */ > > Why only 4? > this is higher 4 bits of 36 bit addressing..
Make it clear in the comment.
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> > > +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
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