Re: [PATCH] drm/rockchip: fix clk enable disable mismatch in vop_crtc_mode_set

Am Samstag, 31. Januar 2015, 13:43:23 schrieb Daniel Kurtz:

Hi Heiko,

On Sat, Jan 31, 2015 at 3:28 AM, Heiko Stübner heiko@sntech.de wrote:

...

The function disables the dclk at the beginning, so don't simply return when an error happens, but instead enable the clock again, so that enable and disable calls are balanced.

This function is a bit of a disaster, and needs fixing some day. AFAICT, the dclk_rst is actually ignored if dclk is disabled, so that part doesn't even work.

...

ret_clk is introduced to hold the clk_enable result and not mangle the original error code.

Signed-off-by: Heiko Stuebner heiko@sntech.de

---

drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c index 04b619a..c0387f7 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c @@ -852,7 +852,7 @@ static int vop_crtc_mode_set(struct drm_crtc *crtc,

    u16 vsync_len = adjusted_mode->vsync_end -
    adjusted_mode->vsync_start;
    u16 vact_st = adjusted_mode->vtotal - adjusted_mode->vsync_start;
    u16 vact_end = vact_st + vdisplay;

•   int ret;
  

•   int ret, ret_clk;
  
    uint32_t val;
  
    /*
  
  

@@ -874,7 +874,8 @@ static int vop_crtc_mode_set(struct drm_crtc *crtc,

    default:
            DRM_ERROR("unsupport connector_type[%d]\n",

                      vop->connector_type);

•           return -EINVAL;
  

•           ret = -EINVAL;
  

•           goto out;
  
    };
    VOP_CTRL_SET(vop, out_mode, vop->connector_out_mode);
  
  

@@ -897,7 +898,7 @@ static int vop_crtc_mode_set(struct drm_crtc *crtc,

    ret = vop_crtc_mode_set_base(crtc, x, y, fb);
    if (ret)

•           return ret;
  

•           goto out;
  
    /*
  
     * reset dclk, take all mode config affect, so the clk would run
     in
  
  

@@ -908,13 +909,14 @@ static int vop_crtc_mode_set(struct drm_crtc *crtc,

    reset_control_deassert(vop->dclk_rst);

    clk_set_rate(vop->dclk, adjusted_mode->clock * 1000);

•   ret = clk_enable(vop->dclk);
  

•   if (ret < 0) {
  

•           dev_err(vop->dev, "failed to enable dclk - %d\n", ret);
  

•           return ret;
  

+out:

•   ret_clk = clk_enable(vop->dclk);
  

•   if (ret_clk < 0) {
  

•           dev_err(vop->dev, "failed to enable dclk - %d\n",
  

ret_clk);

•           return ret_clk;
  

Doesn't this swallow ret ? I thought the point was to still return the original error?

I think if even the reenabling of the clock fails, there must be something _really_ wrong with the system [enabled before and all] - so if this also returns an error after the core functionality failed already, it doesn't really matter anymore which error we return :-) .

The original point was to not overwrite the actual error (in ret) in the case where clk_enable simply returns 0 .

Heiko