On 12.12.2022 16:33, Jagan Teki wrote:
On Mon, Dec 12, 2022 at 8:52 PM Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote:On 12.12.2022 09:43, Marek Szyprowski wrote:On 12.12.2022 09:32, Jagan Teki wrote:On Mon, Dec 12, 2022 at 1:56 PM Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote:Hi Jagan, On 09.12.2022 16:23, Jagan Teki wrote:The existing drm panels and bridges in Exynos required host initialization during the first DSI command transfer even though the initialization was done before. This host reinitialization is handled via DSIM_STATE_REINITIALIZED flag and triggers from host transfer. Do this exclusively for Exynos. Initial logic is derived from Marek Szyprowski changes. Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Signed-off-by: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx> --- Changes from v9: - derived from v8 - added comments drivers/gpu/drm/bridge/samsung-dsim.c | 15 ++++++++++++++- include/drm/bridge/samsung-dsim.h | 5 +++-- 2 files changed, 17 insertions(+), 3 deletions(-)The following chunk is missing compared to v8: diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c index 6e9ad955ebd3..6a9403cb92ae 100644 --- a/drivers/gpu/drm/bridge/samsung-dsim.c +++ b/drivers/gpu/drm/bridge/samsung-dsim.c @@ -1315,7 +1315,9 @@ static int samsung_dsim_init(struct samsung_dsim *dsi, unsigned int flag) return 0; samsung_dsim_reset(dsi); - samsung_dsim_enable_irq(dsi); + + if (!(dsi->state & DSIM_STATE_INITIALIZED)) + samsung_dsim_enable_irq(dsi);Is this really required? does it make sure that the IRQ does not enable twice?That's what that check does. Without the 'if (!(dsi->state & DSIM_STATE_INITIALIZED))' check, the irqs will be enabled twice (first from pre_enable, then from the first transfer), what leads to a warning from irq core.I've just noticed that we also would need to clear the DSIM_STATE_REINITIALIZED flag in dsim_suspend. However I've found that a bit simpler patch would keep the current code flow for Exynos instead of this reinitialization hack. This can be applied on the "[PATCH v9 09/18] drm: bridge: samsung-dsim: Add host init in pre_enable" patch: diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c index 0b2e52585485..acc95c61ae45 100644 --- a/drivers/gpu/drm/bridge/samsung-dsim.c +++ b/drivers/gpu/drm/bridge/samsung-dsim.c @@ -1291,9 +1291,11 @@ static void samsung_dsim_atomic_pre_enable(struct drm_bridge *bridge, dsi->state |= DSIM_STATE_ENABLED; - ret = samsung_dsim_init(dsi, DSIM_STATE_INITIALIZED); - if (ret) - return; + if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) { + ret = samsung_dsim_init(dsi, DSIM_STATE_INITIALIZED); + if (ret) + return; + }Sorry, I don't understand this. Does it mean Exynos doesn't need to init host in pre_enable? If I remember correctly even though the host is initialized it has to reinitialize during the first transfer - This is what the Exynos requirement is. Please correct or explain here.
This is a matter of enabling power regulator(s) in the right order and doing the host initialization in the right moment. It was never a matter of re-initialization. See the current code for the reference (it uses the same approach as my above change). I've already explained that here:
https://lore.kernel.org/all/e96197f9-948a-997e-5453-9f9d179b5f5a@xxxxxxxxxxx/
If you would like to see the exact proper moment of the dsi host initialization on the Exynos see the code here:
https://github.com/mszyprow/linux/tree/v5.18-next-20220511-dsi-rework and patches adding mipi_dsi_host_init() to panel/bridge drivers.
Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
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