From mboxrd@z Thu Jan 1 00:00:00 1970 From: architt@codeaurora.org (Archit Taneja) Date: Thu, 2 Feb 2017 15:26:15 +0530 Subject: [PATCH V7 3/4] drm/bridge: Add driver for GE B850v3 LVDS/DP++ Bridge In-Reply-To: <2955-5891d280-1-64686980@191354544> References: <2955-5891d280-1-64686980@191354544> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/01/2017 05:51 PM, Peter Senna Tschudin wrote: > > On 01 February, 2017 12:35 CET, Daniel Vetter wrote: > >> On Wed, Feb 01, 2017 at 10:58:43AM +0000, Peter Senna Tschudin wrote: >>> Hi Archit, >>> >>> On 01 February, 2017 10:44 CET, Archit Taneja wrote: >>> >>>> >>>> >>>> On 01/30/2017 10:35 PM, Jani Nikula wrote: >>>>> On Sat, 28 Jan 2017, Peter Senna Tschudin wrote: >>>>>> On Thu, Jan 05, 2017 at 01:18:47PM +0530, Archit Taneja wrote: >>>>>> Hi Archit, >>>>>> >>>>>> Thank you for the comments! >>>>>> >>>>>> [...] >>>>>>>> + total_size = (block[EDID_EXT_BLOCK_CNT] + 1) * EDID_LENGTH; >>>>>>>> + if (total_size > EDID_LENGTH) { >>>>>>>> + kfree(block); >>>>>>>> + block = kmalloc(total_size, GFP_KERNEL); >>>>>>>> + if (!block) >>>>>>>> + return NULL; >>>>>>>> + >>>>>>>> + /* Yes, read the entire buffer, and do not skip the first >>>>>>>> + * EDID_LENGTH bytes. >>>>>>>> + */ >>>>>>> >>>>>>> Is this the reason why you aren't using drm_do_get_edid()? >>> >>>>>> >>>>>> Yes, for some hw specific reason, it is necessary to read the entire >>>>>> EDID buffer starting from 0, not block by block. >>>>> >>>>> Hrmh, I'm planning on moving the edid override and firmware edid >>>>> mechanisms at the drm_do_get_edid() level to be able to truly and >>>>> transparently use a different edid. Currently, they're only used for >>>>> modes, really, and lead to some info retrieved from overrides, some from >>>>> the real edid. This kind of hacks will bypass the override/firmware edid >>>>> mechanisms then too. :( >>>> >>>> It seems like there is a HW issue which prevents them from reading EDID >>>> from an offset. So, I'm not sure if it is a hack or a HW limitation. >>> >>>> >>>> One way around this would be to hide the HW requirement in the >>>> get_edid_block func pointer passed to drm_do_get_edid(). This >>>> would, however, result in more i2c reads (equal to # of extension >>>> blocks) than what the patch currently does. >>>> >>>> Peter, if you think doing extra EDID reads isn't too costly on your >>>> platform, you could consider using drm_do_get_edid(). If not, I guess >>>> you'll miss out on the additional functionality Jani is going to add >>> >>>> in the future. >>> >>> My concern is that for almost one year now, every time I fix something >>> one or two new requests are made. I'm happy to fix the driver, but I >>> want a list of the changes that are required to get it upstream, before >>> I make more changes. Can we agree on exactly what is preventing this >>> driver to get upstream? Then I'll fix it. >> >> I think addressing this edid reading question post-merge is perfectly >> fine. Aside, want to keep maintaing your stuff as part of the drm-misc >> group, with the drivers-in-misc experiment? The edid thing was only a suggestion. As Daniel said, it's okay to work on it post merge. Please do fix the minor comments I mentioned in the latest patch set. I'll pull in the first 3 patches once Rob H gives an Ack on the DT bindings patch. The 4th patch needs to go through the SoC maintainer. Thanks, Archit > > Yes, sure! > >> -Daniel >> -- >> Daniel Vetter >> Software Engineer, Intel Corporation >> http://blog.ffwll.ch > > > > > > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project