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fix(kdrv): Bound the drain after a panel read #122

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Merged
jbenedictocenteno merged 2 commits into from
Nov 13, 2026
Merged

fix(kdrv): Bound the drain after a panel read #122

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6d0fb25
fix(kdrv): Bound the drain after a panel read
jbenedictocenteno Nov 13, 2026
b1d5646
fix(kdrv): Say when a panel read's drain stops at its bound
jbenedictocenteno Nov 13, 2026
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14 changes: 13 additions & 1 deletion components/kdrv/display/src/kdrv_display.c
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Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,8 @@ _Static_assert(KDRV_DISPLAY_CACHE_LINE == CONFIG_CACHE_L2_CACHE_LINE_SIZE,
* full after BRIGHT_FIFO_WAIT_MS is reported rather than entered. */
#define BRIGHT_GAP_MS 20U
#define BRIGHT_FIFO_WAIT_MS 50U
/** Words a DCS read drains after its answer, at most: far more than any answer to a one-byte read leaves. */
#define PANEL_READ_DRAIN_MAX 64U

/* DCS commands the panel takes outside the init table. The names are IDF's
* (esp_lcd_panel_commands.h); the casts are the driver's, which wants bytes. */
Expand Down Expand Up @@ -1872,10 +1874,20 @@ static kode_status_t panel_read1(uint8_t cmd, uint8_t *val)
}
uint32_t const w = mipi_dsi_host_ll_gen_read_payload_fifo(&MIPI_DSI_HOST);

while ( !mipi_dsi_host_ll_gen_is_read_fifo_empty(&MIPI_DSI_HOST) )
/* Whatever else the panel sent, at most a FIFO's worth: a FIFO that
* never reads empty is a host that is not there (an emulator without a
* DSI host reads its flags as 0), and the byte asked for is in hand. */
for ( uint32_t i = 0U;
(PANEL_READ_DRAIN_MAX > i) && !mipi_dsi_host_ll_gen_is_read_fifo_empty(&MIPI_DSI_HOST);
++i )
{
(void)mipi_dsi_host_ll_gen_read_payload_fifo(&MIPI_DSI_HOST);
}
if ( !mipi_dsi_host_ll_gen_is_read_fifo_empty(&MIPI_DSI_HOST) )
{
KLOG_W(TAG, "DSI read FIFO still not empty after %u words: the host "
"does not answer", (unsigned)PANEL_READ_DRAIN_MAX);
}
*val = (uint8_t)(w & GRAM_BYTE_MASK);
return KODE_OK;
}
Expand Down