On Mon, 08 Apr 2024, Melissa Wen <mwen@xxxxxxxxxx> wrote: > On 04/08, Jani Nikula wrote: >> On Mon, 08 Apr 2024, Melissa Wen <mwen@xxxxxxxxxx> wrote: >> > On 04/02, Jani Nikula wrote: >> >> On Thu, 21 Mar 2024, Jani Nikula <jani.nikula@xxxxxxxxx> wrote: >> >> > Jani Nikula (4): >> >> > drm/edid: add drm_edid_get_product_id() >> >> > drm/edid: add drm_edid_print_product_id() >> >> > drm/i915/bios: switch to struct drm_edid and struct >> >> > drm_edid_product_id >> >> > drm/i915/bios: return drm_edid_product_id from get_lvds_pnp_id() >> >> >> >> Ping for reviews please? This should be helpful in eradicating one class >> >> of drm_edid_raw() uses. >> > >> > Hi Jani, >> > >> > I took a look at the series. AFAIU your solution with >> > `drm_edid_product_id` mostly fits AMD display driver needs, except that >> > it needs the `product_code` split into two parts (like manufacturer >> > name) because the driver handles prod_code parts to configure a register >> > for audio, as in the path below: >> > >> > 1. https://gitlab.freedesktop.org/drm/kernel/-/blob/drm-next/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c#L113 >> > 2. https://gitlab.freedesktop.org/drm/kernel/-/blob/drm-next/drivers/gpu/drm/amd/display/dc/core/dc_stream.c#L90 >> > 3. https://gitlab.freedesktop.org/drm/kernel/-/blob/drm-next/drivers/gpu/drm/amd/display/dc/dce/dce_audio.c#L873 >> > >> > What do you think on keeping `prod_code` split into two part in >> > `drm_edid_product_id`? >> >> I think having it as "__le16 product_code" is better and >> self-documenting. This is what the spec says it is, so why split it to >> two parts where you always need to wonder about the byte order? > > I have no strong opinion, I was only thinking that two parts would make > this `edid_buf->prod_code[0] | edid_buf->prod_code[1] << 8` operation > more intuitive. > > As you mentioned the currrent product_code format fits specs better, I > understand we can get the same result on amd with: > le16_to_cpu() --> split --> second part shift. Wait, what? No. le16_to_cpu() directly gives you what you want. That's the whole point. No splits, no shifts, no OR-ing. One macro that forces the right byte order for you, as the member is defined __le16. > Anyway, it's certainly not a blocker. The series LGTM. > > Acked-by: Melissa Wen <mwen@xxxxxxxxxx> > >> >> This is how you'd use it: >> >> edid_caps->product_id = le16_to_cpu(id->product_code); This is intended to be an example how to deal with your URL 1 above. BR, Jani. >> >> BR, >> Jani. >> >> > >> > (cc'ing some AMD devs that might have a better understanding of this use case) >> > >> > Thanks a lot for addressing this pending issue! >> > >> > Melissa >> > >> >> >> >> BR, >> >> Jani. >> >> >> >> >> >> > >> >> > drivers/gpu/drm/drm_edid.c | 50 +++++++++++++++++++++++ >> >> > drivers/gpu/drm/i915/display/intel_bios.c | 49 ++++++++++------------ >> >> > include/drm/drm_edid.h | 28 ++++++++++--- >> >> > 3 files changed, 94 insertions(+), 33 deletions(-) >> >> >> >> -- >> >> Jani Nikula, Intel >> >> -- >> Jani Nikula, Intel -- Jani Nikula, Intel
