On Wed, 06 Aug 2025, Jouni Högander <jouni.hogan...@intel.com> wrote:
> Parsed divider p will overflow and is considered being valid divider in
> case pll_ctl == 0.
>
> Fix this by using do while.
>
> Signed-off-by: Jouni Högander <jouni.hogan...@intel.com>
> ---
> drivers/gpu/drm/i915/display/vlv_dsi_pll.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> b/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> index b52463fdec47..f56985c3da54 100644
> --- a/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> +++ b/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> @@ -142,10 +142,10 @@ static int vlv_dsi_pclk(struct intel_encoder *encoder,
> pll_div &= DSI_PLL_M1_DIV_MASK;
> pll_div = pll_div >> DSI_PLL_M1_DIV_SHIFT;
>
> - while (pll_ctl) {
> + do {
> pll_ctl = pll_ctl >> 1;
> p++;
> - }
> + } while (pll_ctl);
> p--;
Alternatively, use p = lfs(pll_ctl), check the return value, and p--
after that?
>
> if (!p) {
--
Jani Nikula, Intel
