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From:   Brian Starkey <Brian.Starkey@arm.com>
To:     "james qian wang (Arm Technology China)" <james.qian.wang@arm.com>
CC:     Ayan Halder <Ayan.Halder@arm.com>,
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        "Jonathan Chai (Arm Technology China)" <Jonathan.Chai@arm.com>,
        "Julien Yin (Arm Technology China)" <Julien.Yin@arm.com>,
        "thomas Sun (Arm Technology China)" <thomas.Sun@arm.com>,
        "Lowry Li (Arm Technology China)" <Lowry.Li@arm.com>,
        "Tiannan Zhu (Arm Technology China)" <Tiannan.Zhu@arm.com>,
        "Yiqi Kang (Arm Technology China)" <Yiqi.Kang@arm.com>,
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Subject: Re: [PATCH] drm/komeda: Added AFBC support for komeda driver
Thread-Topic: [PATCH] drm/komeda: Added AFBC support for komeda driver
Thread-Index: AQHU6tZrSfGY2oLen0KpP248EWVF9aZuCQMAgAeEiACABN9HgA==
Date:   Fri, 24 May 2019 11:10:09 +0000
Message-ID: <20190524111009.beddu67vvx66wvmk@DESKTOP-E1NTVVP.localdomain>
References: <20190404110552.15778-1-james.qian.wang@arm.com>
 <20190516135748.GC1372@arm.com>
 <20190521084552.GA20625@james-ThinkStation-P300>
In-Reply-To: <20190521084552.GA20625@james-ThinkStation-P300>
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Hi,

On Tue, May 21, 2019 at 09:45:58AM +0100, james qian wang (Arm Technology C=
hina) wrote:
> On Thu, May 16, 2019 at 09:57:49PM +0800, Ayan Halder wrote:
> > On Thu, Apr 04, 2019 at 12:06:14PM +0100, james qian wang (Arm Technolo=
gy China) wrote:
> > > =20
> > > +static int
> > > +komeda_fb_afbc_size_check(struct komeda_fb *kfb, struct drm_file *fi=
le,
> > > +			  const struct drm_mode_fb_cmd2 *mode_cmd)
> > > +{
> > > +	struct drm_framebuffer *fb =3D &kfb->base;
> > > +	const struct drm_format_info *info =3D fb->format;
> > > +	struct drm_gem_object *obj;
> > > +	u32 alignment_w =3D 0, alignment_h =3D 0, alignment_header;
> > > +	u32 n_blocks =3D 0, min_size =3D 0;
> > > +
> > > +	obj =3D drm_gem_object_lookup(file, mode_cmd->handles[0]);
> > > +	if (!obj) {
> > > +		DRM_DEBUG_KMS("Failed to lookup GEM object\n");
> > > +		return -ENOENT;
> > > +	}
> > > +
> > > +	switch (fb->modifier & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
> > > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
> > > +		alignment_w =3D 32;
> > > +		alignment_h =3D 8;
> > > +		break;
> > > +	case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
> > > +		alignment_w =3D 16;
> > > +		alignment_h =3D 16;
> > > +		break;
> > > +	default:
> > Can we have something like a warn here ?
>=20
> will add a WARN here.
>=20

I think it's better not to. fb->modifier comes from
userspace, so a malicious app could spam us with WARNs, effectively
dos-ing the system. -EINVAL should be sufficient.

Thanks,
-Brian