diff mbox series

[v3,08/13] drm: bridge: samsung-dsim: Add module init, exit

Message ID 20220720155210.365977-9-jagan@amarulasolutions.com
State New
Headers
Series drm: bridge: Add Samsung MIPI DSIM bridge |

Commit Message

Jagan Teki July 20, 2022, 3:52 p.m. UTC 
Add module init and exit functions for the bridge to register
and unregister dsi_driver.

Exynos drm driver stack will register the platform_driver separately
in the common of it's exynos_drm_drv.c including dsi_driver.

Register again would return -EBUSY, so return 0 for such cases as
dsi_driver is already registered.

v3, v2, v1:
* none

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

Comments

Marek Szyprowski July 21, 2022, 11:09 a.m. UTC | #1 
Hi Jagan,

On 20.07.2022 17:52, Jagan Teki wrote:
> Add module init and exit functions for the bridge to register
> and unregister dsi_driver.
>
> Exynos drm driver stack will register the platform_driver separately
> in the common of it's exynos_drm_drv.c including dsi_driver.
>
> Register again would return -EBUSY, so return 0 for such cases as
> dsi_driver is already registered.

I've already pointed that this is a bad style solution. It will also not 
work in the following cases:

1. exynos drm and samsung-dsim compiled as modules - samsung-dsim 
module, once loaded, will register the driver and exynos_drm won't be 
able to register the exynos_dsi.

2. multi-arch case - if one compiles a kernel (disto-style) with drivers 
for both supported architectures (exynos and imx) - in such case it will 
not work on imx, because exynos_drm driver will always register 
exynos_dsi driver first (even if the kernel is booted on non-exynos board).

Best regards
Jagan Teki July 21, 2022, 11:12 a.m. UTC | #2 
Hi Marek,

On Thu, Jul 21, 2022 at 4:39 PM Marek Szyprowski
<m.szyprowski@samsung.com> wrote:
>
> Hi Jagan,
>
> On 20.07.2022 17:52, Jagan Teki wrote:
> > Add module init and exit functions for the bridge to register
> > and unregister dsi_driver.
> >
> > Exynos drm driver stack will register the platform_driver separately
> > in the common of it's exynos_drm_drv.c including dsi_driver.
> >
> > Register again would return -EBUSY, so return 0 for such cases as
> > dsi_driver is already registered.
>
> I've already pointed that this is a bad style solution. It will also not
> work in the following cases:

Yes, I have seen it in v2. (sending again since its part of the series
and resolved other issues on v2)

>
> 1. exynos drm and samsung-dsim compiled as modules - samsung-dsim
> module, once loaded, will register the driver and exynos_drm won't be
> able to register the exynos_dsi.
>
> 2. multi-arch case - if one compiles a kernel (disto-style) with drivers
> for both supported architectures (exynos and imx) - in such case it will
> not work on imx, because exynos_drm driver will always register
> exynos_dsi driver first (even if the kernel is booted on non-exynos board).

Okay. I need to check the best way to handle this - so far this seems
new. any suggestions, please let me know.

Thanks,
Jagan.
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 5eb594ea0bdf..5a0fea30e9e8 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -1737,6 +1737,28 @@  struct platform_driver dsi_driver = {
 	},
 };
 
+static int __init samsung_mipi_dsim_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&dsi_driver);
+
+	/**
+	 * Exynos drm driver stack will register the platform_driver
+	 * separately in the common of it's exynos_drm_drv.c including
+	 * dsi_driver. Register again would return -EBUSY, so return 0
+	 * for such cases as dsi_driver is already registered.
+	 */
+	return ret == -EBUSY ? 0 : ret;
+}
+module_init(samsung_mipi_dsim_init);
+
+static void __exit samsung_mipi_dsim_exit(void)
+{
+	platform_driver_unregister(&dsi_driver);
+}
+module_exit(samsung_mipi_dsim_exit);
+
 MODULE_AUTHOR("Jagan Teki <jagan@amarulasolutions.com>");
 MODULE_DESCRIPTION("Samsung MIPI DSIM controller bridge");
 MODULE_LICENSE("GPL");