At Mon, 13 May 2013 15:37:27 +0800,
Wang Xingchao wrote:
>
> hda_i915 has dependency on i915 module, this patch check whether
> symbol exist before calling API there. If i915 module not loaded it
> will try to load before use.
>
> Signed-off-by: Wang Xingchao <xingchao.wang at linux.intel.com>
You need to manage the symbols more properly. The symbols must be
unreferenced upon the driver unbind. Also, I'm not sure whether
module refcount of i915 is changed via symbol_get. If not, you need
to keep i915 referred until unbind, which calls the corresponding
module_put().
Yet another question is whether it's appropriate to call
request_module_nowait(). What's wrong with a synchronized one?
thanks,
Takashi
> ---
> sound/pci/hda/hda_i915.c | 42 ++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 40 insertions(+), 2 deletions(-)
>
> diff --git a/sound/pci/hda/hda_i915.c b/sound/pci/hda/hda_i915.c
> index 00def82..edf1a08 100644
> --- a/sound/pci/hda/hda_i915.c
> +++ b/sound/pci/hda/hda_i915.c
> @@ -22,16 +22,54 @@
> #include <drm/i915_powerwell.h>
> #include "hda_i915.h"
>
> +const char *name = "i915";
> +static void (*get_power)(const char *name);
> +static void (*put_power)(const char *name);
> +
> /* Power well has impact on Haswell controller and codecs */
> void hda_display_power(bool enable)
> {
> snd_printk(KERN_INFO "HDA display power %s \n", enable ? "Enable" : "Disable");
> +
> + if (!get_power || !put_power)
> + return;
> +
> if (enable)
> - i915_request_power_well("hda");
> + get_power("hda");
> else
> - i915_release_power_well("hda");
> + put_power("hda");
> }
> EXPORT_SYMBOL(hda_display_power);
>
> +static int __init hda_i915_init(void)
> +{
> + struct module *i915;
> + mutex_lock(&module_mutex);
> + i915 = find_module(name);
> + mutex_unlock(&module_mutex);
> +
> + if (!i915)
> + request_module_nowait(name);
> +
> + if (!try_module_get(i915))
> + return -EFAULT;
> +
> + get_power = symbol_get(i915_request_power_well);
> + put_power = symbol_get(i915_release_power_well);
> +
> + module_put(i915);
> + return 0;
> +}
> +
> +#if 0
> +static void __exit hda_i915_exit(void)
> +{
> + drm_pci_exit(&driver, &i915_pci_driver);
> +}
> +
> +module_init(hda_i915_init);
> +module_exit(hda_i915_exit);
> +#endif
> +module_init(hda_i915_init);
> MODULE_DESCRIPTION("HDA power well");
> MODULE_LICENSE("GPL");
> --
> 1.7.9.5
>
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