From mboxrd@z Thu Jan 1 00:00:00 1970 From: Archit Taneja Date: Wed, 10 Apr 2013 09:40:17 +0000 Subject: Re: [PATCH] omapdss: use devm_clk_get() Message-Id: <516530B1.80203@ti.com> List-Id: References: <1365411346-30611-1-git-send-email-archit@ti.com> <51651F25.3020302@ti.com> <516524B8.60205@ti.com> <51652EA4.9010606@ti.com> In-Reply-To: <51652EA4.9010606@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tomi Valkeinen Cc: linux-omap@vger.kernel.org, linux-fbdev@vger.kernel.org On Wednesday 10 April 2013 02:49 PM, Tomi Valkeinen wrote: > On 2013-04-10 11:37, Archit Taneja wrote: >> On Wednesday 10 April 2013 01:43 PM, Tomi Valkeinen wrote: >>> On 2013-04-08 11:55, Archit Taneja wrote: >>>> Use devm_clk_get() instead of clk_get() for dss, and for outputs hdmi >>>> and venc. >>>> This reduces reduces code and simplifies error handling. >>>> >>>> Signed-off-by: Archit Taneja >>>> --- >>>> drivers/video/omap2/dss/dss.c | 18 +++--------------- >>>> drivers/video/omap2/dss/hdmi.c | 16 ++-------------- >>>> drivers/video/omap2/dss/venc.c | 10 +--------- >>>> 3 files changed, 6 insertions(+), 38 deletions(-) >>>> >>>> diff --git a/drivers/video/omap2/dss/dss.c >>>> b/drivers/video/omap2/dss/dss.c >>>> index 054c2a2..645b3bc 100644 >>>> --- a/drivers/video/omap2/dss/dss.c >>>> +++ b/drivers/video/omap2/dss/dss.c >>>> @@ -767,13 +767,11 @@ int dss_dpi_select_source(enum omap_channel >>>> channel) >>>> static int dss_get_clocks(void) >>>> { >>>> struct clk *clk; >>>> - int r; >>>> >>>> - clk = clk_get(&dss.pdev->dev, "fck"); >>>> + clk = devm_clk_get(&dss.pdev->dev, "fck"); >>>> if (IS_ERR(clk)) { >>>> DSSERR("can't get clock fck\n"); >>>> - r = PTR_ERR(clk); >>>> - goto err; >>>> + return PTR_ERR(clk); >>>> } >>>> >>>> dss.dss_clk = clk; >>>> @@ -782,8 +780,7 @@ static int dss_get_clocks(void) >>>> clk = clk_get(NULL, dss.feat->clk_name); >>>> if (IS_ERR(clk)) { >>>> DSSERR("Failed to get %s\n", dss.feat->clk_name); >>>> - r = PTR_ERR(clk); >>>> - goto err; >>>> + return PTR_ERR(clk); >>>> } >>>> } else { >>>> clk = NULL; >>>> @@ -792,21 +789,12 @@ static int dss_get_clocks(void) >>>> dss.dpll4_m4_ck = clk; >>>> >>>> return 0; >>>> - >>>> -err: >>>> - if (dss.dss_clk) >>>> - clk_put(dss.dss_clk); >>>> - if (dss.dpll4_m4_ck) >>>> - clk_put(dss.dpll4_m4_ck); >>>> - >>>> - return r; >>>> } >>> >>> Why didn't you use devm_clk_get for the dpll4_m4_ck clock also? >> >> clk_get of dpll4_m4_ck isn't tied to a device: >> >> clk = clk_get(NULL, dss.feat->clk_name); >> >> We can't use devm_clk_get() if we don't tie it to a device, right? > > Ah, true. > >> I think the dss.dss_clk clock above is same as the dpll4_m4_ck for all >> OMAPs. We could probably remove the dpll4_m4_clk all together, and use >> dss_clk to get the rate of DSS_FCK coming from PRCM. > > Hmm, no, if I recall right, dpll4_m4_clk is the parent of dss clock (or > parent of the parent of...), and the dss_fck_multiplier affects the > resulting dss fck. Or something like that. It's a bit messy, especially > as we can't just use the dss fck to change the rate, we need to change > the rate at the parent for some reason. Ah ok, I remember it now. One of the DPLL's divider's output is DSS_FCK. We get the parent's rate and iterate through all the possible hsdivider values to get the closest pixel clock. We don't/can't change dpll4_m4_clk as such, we just need to know it's rate for our calculations. So yes, we need dpll4_m4_clk, we just need to rename it to a better thing. Like dss_clk_parent. Anyway, Archit