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Message-ID: <CAA8EJpoF1B4mARmSmEhq9qUfMFxCF-+W1AVDnOLniM6F67=yvw@mail.gmail.com>
Date: Fri, 13 Dec 2024 02:28:11 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>, Paloma Arellano <quic_parellan@...cinc.com>,
Douglas Anderson <dianders@...omium.org>, Stephen Boyd <swboyd@...omium.org>,
linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 09/14] drm/msm/dp: use msm_dp_utils_pack_sdp_header()
for audio packets
On Fri, 13 Dec 2024 at 01:53, Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
>
>
>
> On 12/12/2024 2:28 PM, Dmitry Baryshkov wrote:
> > On Thu, 12 Dec 2024 at 23:41, Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
> >>
> >>
> >>
> >> On 12/11/2024 3:41 PM, Dmitry Baryshkov wrote:
> >>> Use msm_dp_utils_pack_sdp_header() and call msm_dp_write_link() directly
> >>> to program audio packet data. Use 0 as Packet ID, as it was not
> >>> programmed earlier.
> >>>
> >>> Reviewed-by: Stephen Boyd <swboyd@...omium.org>
> >>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> >>> ---
> >>> drivers/gpu/drm/msm/dp/dp_audio.c | 288 +++++++++-----------------------------
> >>> 1 file changed, 66 insertions(+), 222 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/msm/dp/dp_audio.c b/drivers/gpu/drm/msm/dp/dp_audio.c
> >>> index 5cbb11986460d1e4ed1890bdf66d0913e013083c..1aa52d5cc08684a49102e45ed6e40ac2b13497c7 100644
> >>> --- a/drivers/gpu/drm/msm/dp/dp_audio.c
> >>> +++ b/drivers/gpu/drm/msm/dp/dp_audio.c
> >>> @@ -14,6 +14,7 @@
> >>> #include "dp_catalog.h"
> >>> #include "dp_audio.h"
> >>> #include "dp_panel.h"
> >>> +#include "dp_reg.h"
> >>> #include "dp_display.h"
> >>> #include "dp_utils.h"
> >>>
> >>> @@ -28,251 +29,94 @@ struct msm_dp_audio_private {
> >>> struct msm_dp_audio msm_dp_audio;
> >>> };
> >>>
> >>> -static u32 msm_dp_audio_get_header(struct msm_dp_catalog *catalog,
> >>> - enum msm_dp_catalog_audio_sdp_type sdp,
> >>> - enum msm_dp_catalog_audio_header_type header)
> >>> -{
> >>> - return msm_dp_catalog_audio_get_header(catalog, sdp, header);
> >>> -}
> >>> -
> >>> -static void msm_dp_audio_set_header(struct msm_dp_catalog *catalog,
> >>> - u32 data,
> >>> - enum msm_dp_catalog_audio_sdp_type sdp,
> >>> - enum msm_dp_catalog_audio_header_type header)
> >>> -{
> >>> - msm_dp_catalog_audio_set_header(catalog, sdp, header, data);
> >>> -}
> >>> -
> >>> static void msm_dp_audio_stream_sdp(struct msm_dp_audio_private *audio)
> >>> {
> >>> struct msm_dp_catalog *catalog = audio->catalog;
> >>> - u32 value, new_value;
> >>> - u8 parity_byte;
> >>> -
> >>> - /* Config header and parity byte 1 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_STREAM, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - new_value = 0x02;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_1_BIT)
> >>> - | (parity_byte << PARITY_BYTE_1_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 1: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_STREAM, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - /* Config header and parity byte 2 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_STREAM, DP_AUDIO_SDP_HEADER_2);
> >>> - new_value = value;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_2_BIT)
> >>> - | (parity_byte << PARITY_BYTE_2_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 2: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> -
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_STREAM, DP_AUDIO_SDP_HEADER_2);
> >>> -
> >>> - /* Config header and parity byte 3 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_STREAM, DP_AUDIO_SDP_HEADER_3);
> >>> -
> >>> - new_value = audio->channels - 1;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_3_BIT)
> >>> - | (parity_byte << PARITY_BYTE_3_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 3: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> -
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_STREAM, DP_AUDIO_SDP_HEADER_3);
> >>> + struct dp_sdp_header sdp_hdr = {
> >>> + .HB0 = 0x00,
> >>> + .HB1 = 0x02,
> >>> + .HB2 = 0x00,
> >>> + .HB3 = audio->channels - 1,
> >>> + };
> >>> + u32 header[2];
> >>> +
> >>> + msm_dp_utils_pack_sdp_header(&sdp_hdr, header);
> >>> +
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_STREAM_0, header[0]);
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_STREAM_1, header[1]);
> >>> }
> >>
> >> This patch is changing the programming behavior.
> >>
> >> Earlier it was using a read/modify/write on each register. Now, its just
> >> a write. I checked a few chipsets, the reset value of registers was 0,
> >> so that part is okay.
> >
> > Except that it was not a correct RMW, it was read, OR new data without
> > clearing the bitfield, write. So it has been working mostly by a
> > miracle,
> >
> >>
> >> But, for the MMSS_DP_AUDIO_STREAM_0 register, earlier we were writing
> >> only the upper nibble, that is bits 15:0 of DP_AUDIO_SDP_HEADER_0 was
> >> kept as-it-is, but now this patch is changing that to 0. What was the
> >> reason for that change?
> >
> > It is described in the commit message: "Use 0 as Packet ID, as it was not
> > programmed earlier."
> >
>
> The part of using 0 as Packet ID is but not the behavior of changing the
> RMW which is also pretty significant. That was all happening under the hood.
No. It is explicitly mentioned in the commit message. It's not under the hood.
>
> >>
> >> This is true for all the APIs being touched in this file.
> >>
> >> I guess the whole point of having that audio map in the catalog was to
> >> preserve the read values of these registers. I have to check what was
> >> the reason behind that as once again this was before I worked on this
> >> driver as well.
> >>
> >> So technically there are two parts to this change:
> >>
> >> 1) dropping read for each header and directly just writing it
> >> 2) Writing the registers directly instead of going through catalog
> >>
> >> It seems like (1) and (2) are independent. I hope (1) was not the reason
> >> to have started this whole rework.
> >
> > Yes, the driver spends a lot of effort to preserve the data that will
> > be rewritten when the function is called to write the next header
> > byte. So it is useless. Only HB0 has been preserved, PacketID. If for
> > some reason we are generating a stream with the non-zero ID, it should
> > be explicit, not implicitly 'preserved'.
> >
>
> I am trying to understand why this was being preserved. Audio
> programming is half in DP driver and half in ADSP. I dont know if the
> expectation was that packet ID will be programmed elsewhere and not in
> HLOS code hence it was preserved.
>
> > So, the reasons were:
> > - fix the RMW cycles to drop old values from the registers
> > - use new msm_dp_utils_pack_sdp_header()
> > - get rid of the useless indirection through the catalog and enum
> > msm_dp_catalog_audio_header_type
> > - write registers in an efficient way.
> > - if we ever have a set of functions to handle DP infoframes (like we
> > do for HDMI), make the MSM DP driver ready to be converted to such
> > functions.
>
>
> The only reason the current driver needed to go through the catalog map
> was that it was trying to write one header at a time. And in the
> registers, 2 headers are mapped to one register. So a map was needed. I
> do not know the reason for breaking up the writes into one header at a
> time like I already mentioned so I am trying to gather that info.
> Without knowing the reason it might seem useless but its my duty to make
> sure nothing was overlooked.
Sure!
>
>
>
> >
> >>
> >>>
> >>> static void msm_dp_audio_timestamp_sdp(struct msm_dp_audio_private *audio)
> >>> {
> >>> struct msm_dp_catalog *catalog = audio->catalog;
> >>> - u32 value, new_value;
> >>> - u8 parity_byte;
> >>> -
> >>> - /* Config header and parity byte 1 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_TIMESTAMP, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - new_value = 0x1;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_1_BIT)
> >>> - | (parity_byte << PARITY_BYTE_1_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 1: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_TIMESTAMP, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - /* Config header and parity byte 2 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_TIMESTAMP, DP_AUDIO_SDP_HEADER_2);
> >>> -
> >>> - new_value = 0x17;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_2_BIT)
> >>> - | (parity_byte << PARITY_BYTE_2_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 2: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_TIMESTAMP, DP_AUDIO_SDP_HEADER_2);
> >>> -
> >>> - /* Config header and parity byte 3 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_TIMESTAMP, DP_AUDIO_SDP_HEADER_3);
> >>> -
> >>> - new_value = (0x0 | (0x11 << 2));
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_3_BIT)
> >>> - | (parity_byte << PARITY_BYTE_3_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 3: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_TIMESTAMP, DP_AUDIO_SDP_HEADER_3);
> >>> + struct dp_sdp_header sdp_hdr = {
> >>> + .HB0 = 0x00,
> >>> + .HB1 = 0x01,
> >>> + .HB2 = 0x17,
> >>> + .HB3 = 0x0 | (0x11 << 2),
> >>> + };
> >>> + u32 header[2];
> >>> +
> >>> + msm_dp_utils_pack_sdp_header(&sdp_hdr, header);
> >>> +
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_TIMESTAMP_0, header[0]);
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_TIMESTAMP_1, header[1]);
> >>> }
> >>>
> >>> static void msm_dp_audio_infoframe_sdp(struct msm_dp_audio_private *audio)
> >>> {
> >>> struct msm_dp_catalog *catalog = audio->catalog;
> >>> - u32 value, new_value;
> >>> - u8 parity_byte;
> >>> -
> >>> - /* Config header and parity byte 1 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_INFOFRAME, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - new_value = 0x84;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_1_BIT)
> >>> - | (parity_byte << PARITY_BYTE_1_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 1: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_INFOFRAME, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - /* Config header and parity byte 2 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_INFOFRAME, DP_AUDIO_SDP_HEADER_2);
> >>> -
> >>> - new_value = 0x1b;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_2_BIT)
> >>> - | (parity_byte << PARITY_BYTE_2_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 2: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_INFOFRAME, DP_AUDIO_SDP_HEADER_2);
> >>> -
> >>> - /* Config header and parity byte 3 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_INFOFRAME, DP_AUDIO_SDP_HEADER_3);
> >>> -
> >>> - new_value = (0x0 | (0x11 << 2));
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_3_BIT)
> >>> - | (parity_byte << PARITY_BYTE_3_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 3: value = 0x%x, parity_byte = 0x%x\n",
> >>> - new_value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_INFOFRAME, DP_AUDIO_SDP_HEADER_3);
> >>> + struct dp_sdp_header sdp_hdr = {
> >>> + .HB0 = 0x00,
> >>> + .HB1 = 0x84,
> >>> + .HB2 = 0x1b,
> >>> + .HB3 = 0x0 | (0x11 << 2),
> >>> + };
> >>> + u32 header[2];
> >>> +
> >>> + msm_dp_utils_pack_sdp_header(&sdp_hdr, header);
> >>> +
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_INFOFRAME_0, header[0]);
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_INFOFRAME_1, header[1]);
> >>> }
> >>>
> >>> static void msm_dp_audio_copy_management_sdp(struct msm_dp_audio_private *audio)
> >>> {
> >>> struct msm_dp_catalog *catalog = audio->catalog;
> >>> - u32 value, new_value;
> >>> - u8 parity_byte;
> >>> -
> >>> - /* Config header and parity byte 1 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_COPYMANAGEMENT, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - new_value = 0x05;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_1_BIT)
> >>> - | (parity_byte << PARITY_BYTE_1_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 1: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_COPYMANAGEMENT, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - /* Config header and parity byte 2 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_COPYMANAGEMENT, DP_AUDIO_SDP_HEADER_2);
> >>> -
> >>> - new_value = 0x0F;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_2_BIT)
> >>> - | (parity_byte << PARITY_BYTE_2_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 2: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_COPYMANAGEMENT, DP_AUDIO_SDP_HEADER_2);
> >>> -
> >>> - /* Config header and parity byte 3 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_COPYMANAGEMENT, DP_AUDIO_SDP_HEADER_3);
> >>> -
> >>> - new_value = 0x0;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_3_BIT)
> >>> - | (parity_byte << PARITY_BYTE_3_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 3: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_COPYMANAGEMENT, DP_AUDIO_SDP_HEADER_3);
> >>> + struct dp_sdp_header sdp_hdr = {
> >>> + .HB0 = 0x00,
> >>> + .HB1 = 0x05,
> >>> + .HB2 = 0x0f,
> >>> + .HB3 = 0x00,
> >>> + };
> >>> + u32 header[2];
> >>> +
> >>> + msm_dp_utils_pack_sdp_header(&sdp_hdr, header);
> >>> +
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_COPYMANAGEMENT_0, header[0]);
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_COPYMANAGEMENT_1, header[1]);
> >>> }
> >>>
> >>> static void msm_dp_audio_isrc_sdp(struct msm_dp_audio_private *audio)
> >>> {
> >>> struct msm_dp_catalog *catalog = audio->catalog;
> >>> - u32 value, new_value;
> >>> - u8 parity_byte;
> >>> -
> >>> - /* Config header and parity byte 1 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_ISRC, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - new_value = 0x06;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_1_BIT)
> >>> - | (parity_byte << PARITY_BYTE_1_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 1: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_ISRC, DP_AUDIO_SDP_HEADER_1);
> >>> -
> >>> - /* Config header and parity byte 2 */
> >>> - value = msm_dp_audio_get_header(catalog,
> >>> - DP_AUDIO_SDP_ISRC, DP_AUDIO_SDP_HEADER_2);
> >>> -
> >>> - new_value = 0x0F;
> >>> - parity_byte = msm_dp_utils_calculate_parity(new_value);
> >>> - value |= ((new_value << HEADER_BYTE_2_BIT)
> >>> - | (parity_byte << PARITY_BYTE_2_BIT));
> >>> - drm_dbg_dp(audio->drm_dev,
> >>> - "Header Byte 2: value = 0x%x, parity_byte = 0x%x\n",
> >>> - value, parity_byte);
> >>> - msm_dp_audio_set_header(catalog, value,
> >>> - DP_AUDIO_SDP_ISRC, DP_AUDIO_SDP_HEADER_2);
> >>> + struct dp_sdp_header sdp_hdr = {
> >>> + .HB0 = 0x00,
> >>> + .HB1 = 0x06,
> >>> + .HB2 = 0x0f,
> >>> + .HB3 = 0x00,
> >>> + };
> >>> + u32 header[2];
> >>> + u32 reg;
> >>> +
> >>> + /* XXX: is it necessary to preserve this field? */
> >>> + reg = msm_dp_read_link(catalog, MMSS_DP_AUDIO_ISRC_1);
> >>> + sdp_hdr.HB3 = FIELD_GET(HEADER_3_MASK, reg);
> >>> +
> >>> + msm_dp_utils_pack_sdp_header(&sdp_hdr, header);
> >>> +
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_ISRC_0, header[0]);
> >>> + msm_dp_write_link(catalog, MMSS_DP_AUDIO_ISRC_1, header[1]);
> >>> }
> >>>
> >>> static void msm_dp_audio_setup_sdp(struct msm_dp_audio_private *audio)
> >>>
> >
> >
> >
--
With best wishes
Dmitry
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