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Date: Mon, 13 Feb 2023 13:41:47 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Konrad Dybcio <konrad.dybcio@...aro.org>,
linux-arm-msm@...r.kernel.org, andersson@...nel.org,
agross@...nel.org, krzysztof.kozlowski@...aro.org
Cc: marijn.suijten@...ainline.org, Rob Clark <robdclark@...il.com>,
Abhinav Kumar <quic_abhinavk@...cinc.com>,
Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Douglas Anderson <dianders@...omium.org>,
Loic Poulain <loic.poulain@...aro.org>,
Neil Armstrong <neil.armstrong@...aro.org>,
Vinod Koul <vkoul@...nel.org>,
Vladimir Lypak <vladimir.lypak@...il.com>,
dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/10] drm/msm/dsi: Zero-terminate
msm_dsi_config::io_start
On 13/02/2023 11:18, Konrad Dybcio wrote:
>
>
> On 11.02.2023 14:19, Dmitry Baryshkov wrote:
>> On 11/02/2023 13:51, Konrad Dybcio wrote:
>>> In preparation for supporting multiple sets of possible base registers,
>>> Zero-terminate the array that contains them to remove the need of
>>> specifying num_dsi for each set.
>>>
>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
>>> ---
>>> drivers/gpu/drm/msm/dsi/dsi_cfg.c | 39 ++++++++++--------------------
>>> drivers/gpu/drm/msm/dsi/dsi_cfg.h | 4 +--
>>> drivers/gpu/drm/msm/dsi/dsi_host.c | 2 +-
>>> 3 files changed, 16 insertions(+), 29 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_cfg.c b/drivers/gpu/drm/msm/dsi/dsi_cfg.c
>>> index 068d45b3a8f0..5f62c563bd1c 100644
>>> --- a/drivers/gpu/drm/msm/dsi/dsi_cfg.c
>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_cfg.c
>>> @@ -22,9 +22,8 @@ static const struct msm_dsi_config apq8064_dsi_cfg = {
>>> .bus_clk_names = dsi_v2_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_v2_bus_clk_names),
>>> .io_start = {
>>> - { 0x4700000, 0x5800000 },
>>> + { 0x4700000, 0x5800000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const char * const dsi_6g_bus_clk_names[] = {
>>> @@ -44,9 +43,8 @@ static const struct msm_dsi_config msm8974_apq8084_dsi_cfg = {
>>> .bus_clk_names = dsi_6g_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_6g_bus_clk_names),
>>> .io_start = {
>>> - { 0xfd922800, 0xfd922b00 },
>>> + { 0xfd922800, 0xfd922b00, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const char * const dsi_8916_bus_clk_names[] = {
>>> @@ -65,9 +63,8 @@ static const struct msm_dsi_config msm8916_dsi_cfg = {
>>> .bus_clk_names = dsi_8916_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_8916_bus_clk_names),
>>> .io_start = {
>>> - { 0x1a98000 },
>>> + { 0x1a98000, 0 },
>>> },
>>> - .num_dsi = 1,
>>> };
>>> static const char * const dsi_8976_bus_clk_names[] = {
>>> @@ -86,9 +83,8 @@ static const struct msm_dsi_config msm8976_dsi_cfg = {
>>> .bus_clk_names = dsi_8976_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_8976_bus_clk_names),
>>> .io_start = {
>>> - { 0x1a94000, 0x1a96000 },
>>> + { 0x1a94000, 0x1a96000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const struct regulator_bulk_data msm8994_dsi_regulators[] = {
>>> @@ -107,9 +103,8 @@ static const struct msm_dsi_config msm8994_dsi_cfg = {
>>> .bus_clk_names = dsi_6g_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_6g_bus_clk_names),
>>> .io_start = {
>>> - { 0xfd998000, 0xfd9a0000 },
>>> + { 0xfd998000, 0xfd9a0000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const char * const dsi_8996_bus_clk_names[] = {
>>> @@ -129,9 +124,8 @@ static const struct msm_dsi_config msm8996_dsi_cfg = {
>>> .bus_clk_names = dsi_8996_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_8996_bus_clk_names),
>>> .io_start = {
>>> - { 0x994000, 0x996000 },
>>> + { 0x994000, 0x996000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const char * const dsi_msm8998_bus_clk_names[] = {
>>> @@ -150,9 +144,8 @@ static const struct msm_dsi_config msm8998_dsi_cfg = {
>>> .bus_clk_names = dsi_msm8998_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_msm8998_bus_clk_names),
>>> .io_start = {
>>> - { 0xc994000, 0xc996000 },
>>> + { 0xc994000, 0xc996000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const char * const dsi_sdm660_bus_clk_names[] = {
>>> @@ -170,9 +163,8 @@ static const struct msm_dsi_config sdm660_dsi_cfg = {
>>> .bus_clk_names = dsi_sdm660_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_sdm660_bus_clk_names),
>>> .io_start = {
>>> - { 0xc994000, 0xc996000 },
>>> + { 0xc994000, 0xc996000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const char * const dsi_sdm845_bus_clk_names[] = {
>>> @@ -194,9 +186,8 @@ static const struct msm_dsi_config sdm845_dsi_cfg = {
>>> .bus_clk_names = dsi_sdm845_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_sdm845_bus_clk_names),
>>> .io_start = {
>>> - { 0xae94000, 0xae96000 },
>>> + { 0xae94000, 0xae96000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const struct regulator_bulk_data sm8550_dsi_regulators[] = {
>>> @@ -210,9 +201,8 @@ static const struct msm_dsi_config sm8550_dsi_cfg = {
>>> .bus_clk_names = dsi_sdm845_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_sdm845_bus_clk_names),
>>> .io_start = {
>>> - { 0xae94000, 0xae96000 },
>>> + { 0xae94000, 0xae96000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const struct regulator_bulk_data sc7180_dsi_regulators[] = {
>>> @@ -226,9 +216,8 @@ static const struct msm_dsi_config sc7180_dsi_cfg = {
>>> .bus_clk_names = dsi_sc7180_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_sc7180_bus_clk_names),
>>> .io_start = {
>>> - { 0xae94000 },
>>> + { 0xae94000, 0 },
>>> },
>>> - .num_dsi = 1,
>>> };
>>> static const char * const dsi_sc7280_bus_clk_names[] = {
>>> @@ -246,9 +235,8 @@ static const struct msm_dsi_config sc7280_dsi_cfg = {
>>> .bus_clk_names = dsi_sc7280_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_sc7280_bus_clk_names),
>>> .io_start = {
>>> - { 0xae94000, 0xae96000 },
>>> + { 0xae94000, 0xae96000, 0 },
>>> },
>>> - .num_dsi = 2,
>>> };
>>> static const char * const dsi_qcm2290_bus_clk_names[] = {
>>> @@ -266,9 +254,8 @@ static const struct msm_dsi_config qcm2290_dsi_cfg = {
>>> .bus_clk_names = dsi_qcm2290_bus_clk_names,
>>> .num_bus_clks = ARRAY_SIZE(dsi_qcm2290_bus_clk_names),
>>> .io_start = {
>>> - { 0x5e94000 },
>>> + { 0x5e94000, 0 },
>>> },
>>> - .num_dsi = 1,
>>> };
>>> static const struct msm_dsi_host_cfg_ops msm_dsi_v2_host_ops = {
>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_cfg.h b/drivers/gpu/drm/msm/dsi/dsi_cfg.h
>>> index df9f09876ccb..03493cc6b772 100644
>>> --- a/drivers/gpu/drm/msm/dsi/dsi_cfg.h
>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_cfg.h
>>> @@ -41,8 +41,8 @@ struct msm_dsi_config {
>>> int num_regulators;
>>> const char * const *bus_clk_names;
>>> const int num_bus_clks;
>>> - const resource_size_t io_start[VARIANTS_MAX][DSI_MAX];
>>> - const int num_dsi;
>>> + /* Allow + 1 entry for the zero-terminator */
>>> + const resource_size_t io_start[VARIANTS_MAX][DSI_MAX + 1];
>>> };
>>> struct msm_dsi_host_cfg_ops {
>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> index 22ba8726b0ea..f5092b4d0757 100644
>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>> @@ -1868,7 +1868,7 @@ static int dsi_host_get_id(struct msm_dsi_host *msm_host)
>>> if (!res)
>>> return -EINVAL;
>>> - for (i = 0; i < cfg->num_dsi; i++) {
>>> + for (i = 0; cfg->io_start[0][i]; i++) {
>>> if (cfg->io_start[0][i] == res->start)
>>> return i;
>>> }
>>
>> I think we have the easier way to do this: always loop towards DSI_MAX. Empty cells will contain the value of 0 which can not match against valid starting address.
> Yep, your approach will save us NUM_ENTRIES*sizeof(u64) memory!
As for me it not about saving memory, but rather about the driver logic.
Compare:
- We have two possible DSI hosts, one which is ocassionally absent thus
the address is 0
vs
- We have a zero-terminated list of 2+1 entries for not more than two
DSI hosts.
>
>>
>> Also please shift this patch to the first place, it will be logical to add VARIANT_MAX after removing num_dsi.
> Ack.
>
> Konrad
>>
--
With best wishes
Dmitry
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