Hi,
On 11/21/23 02:17, Richard Acayan wrote:
> Hello,
>
> On Wed, Nov 01, 2023 at 06:20:17PM +0100, Thierry Reding wrote:
>> From: Thierry Reding <treding@xxxxxxxxxx>
>>
>> The simple-framebuffer device tree bindings document the power-domains
>> property, so make sure that simplefb supports it. This ensures that the
>> power domains remain enabled as long as simplefb is active.
>>
>> v2: - remove unnecessary call to simplefb_detach_genpds() since that's
>> already done automatically by devres
>> - fix crash if power-domains property is missing in DT
>>
>> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
>> ---
>> drivers/video/fbdev/simplefb.c | 93 ++++++++++++++++++++++++++++++++++
>> 1 file changed, 93 insertions(+)
>>
>> diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
>> index 18025f34fde7..fe682af63827 100644
>> --- a/drivers/video/fbdev/simplefb.c
>> +++ b/drivers/video/fbdev/simplefb.c
>> @@ -25,6 +25,7 @@
>> #include <linux/of_clk.h>
>> #include <linux/of_platform.h>
>> #include <linux/parser.h>
>> +#include <linux/pm_domain.h>
>> #include <linux/regulator/consumer.h>
>>
>> static const struct fb_fix_screeninfo simplefb_fix = {
>> @@ -78,6 +79,11 @@ struct simplefb_par {
>> unsigned int clk_count;
>> struct clk **clks;
>> #endif
>> +#if defined CONFIG_OF && defined CONFIG_PM_GENERIC_DOMAINS
>> + unsigned int num_genpds;
>
> This is the cause of the crash that occurred on the older patch series.
> The field is unsigned, a deviation from v6.6:drivers/remoteproc/imx_rproc.c.
>
> Instead of making it signed, this version emits an error whenever the
> count is negative.
I'm not sure what you are trying to say here ?
>> + struct device **genpds;
>> + struct device_link **genpd_links;
>> +#endif
>> #if defined CONFIG_OF && defined CONFIG_REGULATOR
>> bool regulators_enabled;
>> u32 regulator_count;
>> @@ -432,6 +438,89 @@ static void simplefb_regulators_enable(struct simplefb_par *par,
>> static void simplefb_regulators_destroy(struct simplefb_par *par) { }
>> #endif
>>
>> +#if defined CONFIG_OF && defined CONFIG_PM_GENERIC_DOMAINS
>> +static void simplefb_detach_genpds(void *res)
>> +{
>> + struct simplefb_par *par = res;
>> + unsigned int i = par->num_genpds;
>> +
>> + if (par->num_genpds <= 1)
>> + return;
>> +
>> + while (i--) {
>> + if (par->genpd_links[i])
>> + device_link_del(par->genpd_links[i]);
>> +
>> + if (!IS_ERR_OR_NULL(par->genpds[i]))
>> + dev_pm_domain_detach(par->genpds[i], true);
>> + }
>> +}
>> +
>> +static int simplefb_attach_genpds(struct simplefb_par *par,
>> + struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + unsigned int i;
>> + int err;
>> +
>> + err = of_count_phandle_with_args(dev->of_node, "power-domains",
>> + "#power-domain-cells");
>> + if (err < 0) {
>> + dev_info(dev, "failed to parse power-domains: %d\n", err);
>> + return err;
>
> This error path is taken when there is no power-domains property in the
> device tree with err = -ENOENT.
>
> Strangely, this does not suppress the error like the next if statement,
> even though it is possible that nothing is wrong.
>
>> + }
>> +
>> + par->num_genpds = err;
>> +
>> + /*
>> + * Single power-domain devices are handled by the driver core, so
>> + * nothing to do here.
>> + */
>> + if (par->num_genpds <= 1)
>> + return 0;
>> +
>> + par->genpds = devm_kcalloc(dev, par->num_genpds, sizeof(*par->genpds),
>> + GFP_KERNEL);
> <snip>
>> @@ -518,6 +607,10 @@ static int simplefb_probe(struct platform_device *pdev)
>> if (ret < 0)
>> goto error_clocks;
>>
>> + ret = simplefb_attach_genpds(par, pdev);
>> + if (ret < 0)
>> + goto error_regulators;
>
> With the error case specified above, not specifying power-domains (which
> is valid according to dtschema) causes the entire driver to fail
> whenever there are no power domains in the device tree.
>
> On google-sargo, this causes a bug where the framebuffer fails to probe:
>
> [ 0.409290] simple-framebuffer 9c000000.framebuffer: failed to parse power-domains: -2
> [ 0.409340] simple-framebuffer: probe of 9c000000.framebuffer failed with error -2
Ok so this is a problem, sorry for not catching this during review.
I believe that this should be fixed by changing the code to:
err = of_count_phandle_with_args(dev->of_node, "power-domains",
"#power-domain-cells");
if (err < 0) {
if (err == -ENOENT)
return 0;
dev_info(dev, "failed to parse power-domains: %d\n", err);
return err;
}
Can you submit a (tested) patch fixing this? Then I'll push it
to drm-misc-next right away.
Regards,
Hans
