Re: [RFC PATCH 1/2] ACPI / PNP: Don't add "enumeration_by_parent" devices

From: John Garry
Date: Fri Apr 27 2018 - 05:18:15 EST

On 26/04/2018 15:23, John Garry wrote:


On 26/04/2018 15:08, Mika Westerberg wrote:
On Thu, Apr 26, 2018 at 02:49:49PM +0100, John Garry wrote:
diff --git a/drivers/bus/hisi_lpc.c b/drivers/bus/hisi_lpc.c
index 2d4611e..b04425b 100644
--- a/drivers/bus/hisi_lpc.c
+++ b/drivers/bus/hisi_lpc.c
@@ -18,6 +18,8 @@
#include <linux/of_platform.h>
#include <linux/pci.h>
#include <linux/slab.h>
+#include <linux/serial_8250.h>
+#include "../tty/serial/8250/8250.h"

#define DRV_NAME "hisi-lpc"

@@ -345,6 +347,7 @@ static void hisi_lpc_comm_outs(void *hostdata,
long pio,

struct hisi_lpc_mfd_cell {
+ struct plat_serial8250_port serial8250_port;
struct mfd_cell_acpi_match acpi_match;
char name[MFD_CHILD_NAME_LEN];
char pnpid[ACPI_ID_LEN];
@@ -513,10 +516,31 @@ static int hisi_lpc_acpi_probe(struct device
dev_warn(&child->dev, "set resource fail (%d)\n", ret);
return ret;
+ if (!strcmp(acpi_device_hid(child), "HISI1031")) {

Hi Mika,

Hmm, there is a way in struct mfd_cell to match child devices using _HID
so is there something preventing you from using that?

Not that I know about. Can you describe this method? I guess I also
don't need to set the mfd_cell pnpid either for this special case device.

So we using the mfd_cell to match child devices using _HID. At a glance, I don't actually see other drivers to use mfd_cell_acpi_match.pnpid .

Anyway we don't use static tables as we need to update the resources of the cell dynamically. However I do look at a driver like intel_quark_i2c_gpio.c, and this dynamically modifies the value of global mfd_cell array here:

I know the cell array is only used at probe time, but this did not look to be good standard practice to me.