drm/msm/adreno: Add a modparam to skip GPU

During bringup of a new GPU support, it is convenient to have knob to
quickly disable GPU, but keep the display support. This helps to
fallback to 'kms_swrast' in case of bootup issues due to GPU. Add a
modparam to support this.

Signed-off-by: Akhil P Oommen <akhilpo@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/672262/
Link: https://lore.kernel.org/r/20250902-assorted-sept-1-v1-3-f3ec9baed513@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

Author: akhilpo-qcom

drivers/gpu/drm/msm/adreno/adreno_device.c

@@ -24,6 +24,10 @@ bool disable_acd;
 MODULE_PARM_DESC(disable_acd, "Forcefully disable GPU ACD");
 module_param_unsafe(disable_acd, bool, 0400);
 
+static bool skip_gpu;
+MODULE_PARM_DESC(no_gpu, "Disable GPU driver register (0=enable GPU driver register (default), 1=skip GPU driver register");
+module_param(skip_gpu, bool, 0400);
+
 extern const struct adreno_gpulist a2xx_gpulist;
 extern const struct adreno_gpulist a3xx_gpulist;
 extern const struct adreno_gpulist a4xx_gpulist;
@@ -184,6 +188,9 @@ bool adreno_has_gpu(struct device_node *node)
 	uint32_t chip_id;
 	int ret;
 
+	if (skip_gpu)
+		return false;
+
 	ret = find_chipid(node, &chip_id);
 	if (ret)
 		return false;
@@ -404,10 +411,16 @@ static struct platform_driver adreno_driver = {
 
 void __init adreno_register(void)
 {
+	if (skip_gpu)
+		return;
+
 	platform_driver_register(&adreno_driver);
 }
 
 void __exit adreno_unregister(void)
 {
+	if (skip_gpu)
+		return;
+
 	platform_driver_unregister(&adreno_driver);
 }