From mboxrd@z Thu Jan 1 00:00:00 1970 From: architt@codeaurora.org (Archit Taneja) Date: Wed, 1 Feb 2017 15:14:42 +0530 Subject: [PATCH V7 3/4] drm/bridge: Add driver for GE B850v3 LVDS/DP++ Bridge In-Reply-To: <877f5ciilg.fsf@intel.com> References: <4232c88a99f44a24287d04d74b891e2eb139864c.1483301745.git.peter.senna@collabora.com> <759f96e2-43da-45ba-cf8d-55bc1f6e8442@codeaurora.org> <20170128141646.GA21291@collabora.com> <877f5ciilg.fsf@intel.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. Thanks, Archit > > BR, > Jani. > > >> >> [...] >> >> I fixed all your other suggestions. Thank you! >> _______________________________________________ >> dri-devel mailing list >> dri-devel at lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project