The common-clk core expects clk consumers to always call enable/disable
in a balanced manner. The atomisp driver does not call gmin_flisclk_ctrl()
in a balanced manner, so add a clock_on bool and skip redundant calls.

This fixes kernel oops like this one:

[   19.811613] gc0310_s_config S
[   19.811655] ------------[ cut here ]------------
[   19.811664] WARNING: CPU: 1 PID: 720 at drivers/clk/clk.c:594 clk_core_disabl
[   19.811666] Modules linked in: tpm_crb(+) snd_soc_sst_atom_hifi2_platform tpm
[   19.811744] CPU: 1 PID: 720 Comm: systemd-udevd Tainted: G         C OE   4.1
[   19.811746] Hardware name: Insyde T701/T701, BIOS BYT70A.YNCHENG.WIN.007 08/2
[   19.811749] task: ffff988df7ab2500 task.stack: ffffac1400474000
[   19.811752] RIP: 0010:clk_core_disable+0xc0/0x130
...
[   19.811775] Call Trace:
[   19.811783]  clk_core_disable_lock+0x1f/0x30
[   19.811788]  clk_disable+0x1f/0x30
[   19.811794]  gmin_flisclk_ctrl+0x87/0xf0
[   19.811801]  0xffffffffc0528512
[   19.811805]  0xffffffffc05295e2
[   19.811811]  ? acpi_device_wakeup_disable+0x50/0x60
[   19.811815]  ? acpi_dev_pm_attach+0x8e/0xd0
[   19.811818]  ? 0xffffffffc05294d0
[   19.811823]  i2c_device_probe+0x1cd/0x280
[   19.811828]  driver_probe_device+0x2ff/0x450

Fixes: "staging: atomisp: use clock framework for camera clocks"
Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
 .../media/atomisp/platform/intel-mid/atomisp_gmin_platform.c       | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git 
a/drivers/staging/media/atomisp/platform/intel-mid/atomisp_gmin_platform.c 
b/drivers/staging/media/atomisp/platform/intel-mid/atomisp_gmin_platform.c
index 828fe5abd832..6671ebe4ecc9 100644
--- a/drivers/staging/media/atomisp/platform/intel-mid/atomisp_gmin_platform.c
+++ b/drivers/staging/media/atomisp/platform/intel-mid/atomisp_gmin_platform.c
@@ -29,6 +29,7 @@ struct gmin_subdev {
        struct v4l2_subdev *subdev;
        int clock_num;
        int clock_src;
+       bool clock_on;
        struct clk *pmc_clk;
        struct gpio_desc *gpio0;
        struct gpio_desc *gpio1;
@@ -583,6 +584,9 @@ static int gmin_flisclk_ctrl(struct v4l2_subdev *subdev, 
int on)
        struct gmin_subdev *gs = find_gmin_subdev(subdev);
        struct i2c_client *client = v4l2_get_subdevdata(subdev);
 
+       if (gs->clock_on == !!on)
+               return 0;
+
        if (on) {
                ret = clk_set_rate(gs->pmc_clk, gs->clock_src);
 
@@ -591,8 +595,11 @@ static int gmin_flisclk_ctrl(struct v4l2_subdev *subdev, 
int on)
                                gs->clock_src);
 
                ret = clk_prepare_enable(gs->pmc_clk);
+               if (ret == 0)
+                       gs->clock_on = true;
        } else {
                clk_disable_unprepare(gs->pmc_clk);
+               gs->clock_on = false;
        }
 
        return ret;
-- 
2.14.2

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