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SubjectRe: [PATCH 1/2] HISI LPC: Reference static MFD cells for ACPI support
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On Thu, 2018-05-03 at 23:08 +0800, John Garry wrote:
> Currently for ACPI support the driver models the host as
> an MFD. For a device connected to the LPC bus, we dynamically
> create an MFD cell for that device, configuring the cell
> name and ACPI match parameters manually. This makes supporting
> named devices and also special setup handling for certain devices
> awkward, as we would need to introduce some special ACPI device
> handling according to device HID.
>
> To avoid this, create reference static MFD cells for known
> child devices, so when adding an MFD cell we can fix the cell
> platform data as required. For this, a setup callback function
> is added.
>
> For now, only the IPMI cell is added.

> +static const struct mfd_cell *hisi_lpc_acpi_mfd_get_cell(const char
> *hid)
> +{
> + const struct hisi_lpc_acpi_mfd_cell *cell =
> hisi_lpc_acpi_mfd_cells;
> +
> + for (; cell && cell->mfd_cell.name; cell++) {
> + const struct mfd_cell *mfd_cell = &cell->mfd_cell;
> + const struct mfd_cell_acpi_match *acpi_match;
> +
> + acpi_match = mfd_cell->acpi_match;
> + if (!strcmp(acpi_match->pnpid, hid))
> + return mfd_cell;
> + }
> +
> + return NULL;
> +}

I'm not sure I understand why MFD core can't do it (as seen in lines
drivers/mfd/core.c:105 and below).

> + /* allocate the mfd cells, one per child */
> + size = sizeof(*mfd_cells);
> mfd_cells = devm_kcalloc(hostdev, cell_num, size,
> GFP_KERNEL);
> if (!mfd_cells)
> return -ENOMEM;

And since you have structures already, I'm not sure why you need another
allocation for them. Only what you would need is to apply resources and
call devm_mfd_add_devices() per each found device.

> + cell = container_of(mfd_cell_ref, typeof(*cell),
> mfd_cell);

Why we can't iterate over inherited type of objects directly?

--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

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