[PATCH] fbdev: sh_mipi_dsi/sh_mobile_hdmi: clk_round_rate() can return a zero upon error

[Paul Walmsley <pwalmsley@nvidia.com>]

Treat both negative and zero return values from clk_round_rate() as
errors.  This is needed since subsequent patches will convert
clk_round_rate()'s return value to be an unsigned type, rather than a
signed type, since some clock sources can generate rates higher than
(2^31)-1 Hz.

Eventually, when calling clk_round_rate(), only a return value of zero
will be considered a error.  All other values will be considered valid
rates.  The comparison against values less than 0 is kept to preserve
the correct behavior in the meantime.

Signed-off-by: Paul Walmsley <pwalmsley@nvidia.com>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---

Applies on v3.13-rc1.  See also:

http://marc.info/?l=linux-arm-kernel&m\x138542591313620&w=2

  drivers/video/sh_mipi_dsi.c    |    4 +++-
  drivers/video/sh_mobile_hdmi.c |    6 +++---
  2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/video/sh_mipi_dsi.c b/drivers/video/sh_mipi_dsi.c
index 8f6e8ff620d4..510cfb668a0c 100644
--- a/drivers/video/sh_mipi_dsi.c
+++ b/drivers/video/sh_mipi_dsi.c
@@ -494,8 +494,10 @@ static int __init sh_mipi_probe(struct platform_device *pdev)
  		ret = clk_set_rate(mipi->dsit_clk, rate);
  	else
  		ret = rate;
-	if (ret < 0)
+	if (ret <= 0) {
+		ret = -ERANGE;
  		goto esettrate;
+	}

  	dev_dbg(&pdev->dev, "DSI-T clk %lu -> %lu\n", f_current, rate);

diff --git a/drivers/video/sh_mobile_hdmi.c b/drivers/video/sh_mobile_hdmi.c
index 9a33ee0413fb..1e757e54c784 100644
--- a/drivers/video/sh_mobile_hdmi.c
+++ b/drivers/video/sh_mobile_hdmi.c
@@ -818,7 +818,7 @@ static unsigned long sh_hdmi_rate_error(struct sh_hdmi *hdmi,
  	struct sh_mobile_hdmi_info *pdata = dev_get_platdata(hdmi->dev);

  	*hdmi_rate = clk_round_rate(hdmi->hdmi_clk, target);
-	if ((long)*hdmi_rate < 0)
+	if ((long)*hdmi_rate <= 0)
  		*hdmi_rate = clk_get_rate(hdmi->hdmi_clk);

  	rate_error = (long)*hdmi_rate > 0 ? abs(*hdmi_rate - target) : ULONG_MAX;
@@ -1321,8 +1321,8 @@ static int __init sh_hdmi_probe(struct platform_device *pdev)
  	if (rate > 0)
  		rate = sh_hdmi_clk_configure(hdmi, rate, 0);

-	if (rate < 0) {
-		ret = rate;
+	if (rate <= 0) {
+		ret = -EINVAL;
  		goto erate;
  	}


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