Re: [PATCH 03/23] drm: omapdrm: dss: reset dsi module during initialization

Tomi Valkeinen
2016-05-10T12:07:39Z

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On 08/03/16 18:39, Sebastian Reichel wrote:
> From: Tomi Valkeinen <tomi.valkeinen@ti.com>
>
> The Nokia N950's bootloader leaves the DSI module
> in a non-working state. Work around this by resetting
> the DSI module before using it.
>
> Signed-off-By: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Reviewed-By: Sebastian Reichel <sre@kernel.org>
> Tested-By: Sebastian Reichel <sre@kernel.org>
> ---
> drivers/gpu/drm/omapdrm/dss/dsi.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> index 43be4b2a7b05..363a61e6aca7 100644
> --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> @@ -5274,6 +5274,28 @@ static int dsi_init_pll_data(struct platform_device *dsidev)
> return 0;
> }
>
> +static int _dsi_wait_reset(struct platform_device *dsidev)
> +{
> + int t = 0;
> +
> + while (REG_GET(dsidev, DSI_SYSSTATUS, 0, 0) == 0) {
> + if (++t > 5) {
> + DSSERR("soft reset failed\n");
> + return -ENODEV;
> + }
> + udelay(1);
> + }
> +
> + return 0;
> +}
> +
> +static int _dsi_reset(struct platform_device *dsidev)
> +{
> + /* Soft reset */
> + dsi_write_reg(dsidev, DSI_SYSCONFIG, 0x2);
> + return _dsi_wait_reset(dsidev);
> +}
> +
> /* DSI1 HW IP initialisation */
> static int dsi_bind(struct device *dev, struct device *master, void *data)
> {
> @@ -5432,6 +5454,8 @@ static int dsi_bind(struct device *dev, struct device *master, void *data)
> if (r)
> goto err_runtime_get;
>
> + _dsi_reset(dsidev);
> +
> rev = dsi_read_reg(dsidev, DSI_REVISION);
> dev_dbg(&dsidev->dev, "OMAP DSI rev %d.%d\n",
> FLD_GET(rev, 7, 4), FLD_GET(rev, 3, 0));
>

This is good as a prototype, but unfortunately we're not supposed to
reset the IP from the driver. I haven't followed if there's a proper
reset framework yet available, but if not, I think we should do the
reset at the platform code at boot time.

Which actually makes me wonder... We should be doing that reset already
there, in mach-omap2/display.c. I wonder why that's not working...

Tomi

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