diff mbox series

[v5,03/29] drm/omap: pll: fix iteration loop check

Message ID 20201208122855.254819-4-tomi.valkeinen@ti.com (mailing list archive)
State New
Headers show
Series Convert DSI code to use drm_mipi_dsi and drm_panel (second half) | expand

Commit Message

Tomi Valkeinen Dec. 8, 2020, 12:28 p.m. UTC
If the PLL calc function is given bad parameters, n_start/m_start may be
higher than n_stop/m_stop, which leads to the loops iterating through
the whole u32 number space.

Fix this by failing early on such cases.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/gpu/drm/omapdrm/dss/pll.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Sebastian Reichel Dec. 14, 2020, 1:10 p.m. UTC | #1
Hi,

On Tue, Dec 08, 2020 at 02:28:29PM +0200, Tomi Valkeinen wrote:
> If the PLL calc function is given bad parameters, n_start/m_start may be
> higher than n_stop/m_stop, which leads to the loops iterating through
> the whole u32 number space.
> 
> Fix this by failing early on such cases.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---

Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>

-- Sebastian

>  drivers/gpu/drm/omapdrm/dss/pll.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/omapdrm/dss/pll.c b/drivers/gpu/drm/omapdrm/dss/pll.c
> index 1212f3cc52d1..12926218c436 100644
> --- a/drivers/gpu/drm/omapdrm/dss/pll.c
> +++ b/drivers/gpu/drm/omapdrm/dss/pll.c
> @@ -222,6 +222,9 @@ bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin,
>  	n_stop = min((unsigned)(clkin / fint_hw_min), hw->n_max);
>  	n_inc = 1;
>  
> +	if (n_start > n_stop)
> +		return false;
> +
>  	if (hw->errata_i886) {
>  		swap(n_start, n_stop);
>  		n_inc = -1;
> @@ -239,6 +242,9 @@ bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin,
>  				hw->m_max);
>  		m_inc = 1;
>  
> +		if (m_start > m_stop)
> +			continue;
> +
>  		if (hw->errata_i886) {
>  			swap(m_start, m_stop);
>  			m_inc = -1;
> -- 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/omapdrm/dss/pll.c b/drivers/gpu/drm/omapdrm/dss/pll.c
index 1212f3cc52d1..12926218c436 100644
--- a/drivers/gpu/drm/omapdrm/dss/pll.c
+++ b/drivers/gpu/drm/omapdrm/dss/pll.c
@@ -222,6 +222,9 @@  bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin,
 	n_stop = min((unsigned)(clkin / fint_hw_min), hw->n_max);
 	n_inc = 1;
 
+	if (n_start > n_stop)
+		return false;
+
 	if (hw->errata_i886) {
 		swap(n_start, n_stop);
 		n_inc = -1;
@@ -239,6 +242,9 @@  bool dss_pll_calc_a(const struct dss_pll *pll, unsigned long clkin,
 				hw->m_max);
 		m_inc = 1;
 
+		if (m_start > m_stop)
+			continue;
+
 		if (hw->errata_i886) {
 			swap(m_start, m_stop);
 			m_inc = -1;