On Mon, Jun 29, 2026 at 05:01:17PM +0530, Balaji Selvanathan wrote: > The GENI UART hardware can retain stale data in the RX FIFO. > The msm_serial_pending() function was reporting this stale data as > pending input, causing U-Boot to incorrectly assume a key press and > stop at the CLI prompt instead of continuing the boot process. > > Add IRQ status validation to distinguish between legitimate received > data and stale FIFO contents. Check the Secondary IRQ status register > for RX watermark or last flags before reporting pending data. If the > FIFO contains data but no valid IRQ flags are set, ignore it as stale. > > Signed-off-by: Balaji Selvanathan <[email protected]> > --- > drivers/serial/serial_msm_geni.c | 27 ++++++++++++++++++++++----- > 1 file changed, 22 insertions(+), 5 deletions(-) > > diff --git a/drivers/serial/serial_msm_geni.c > b/drivers/serial/serial_msm_geni.c > index 3dca581f68f..6d30f150966 100644 > --- a/drivers/serial/serial_msm_geni.c > +++ b/drivers/serial/serial_msm_geni.c > @@ -424,13 +424,30 @@ static int msm_serial_getc(struct udevice *dev) > static int msm_serial_pending(struct udevice *dev, bool input) > { > struct msm_serial_data *priv = dev_get_priv(dev); > - > - if (input) > - return readl(priv->base + SE_GENI_RX_FIFO_STATUS) & > - RX_FIFO_WC_MSK; > - else > + u32 rx_fifo_status, s_irq_status; > + int result; > + > + if (input) { > + rx_fifo_status = readl(priv->base + SE_GENI_RX_FIFO_STATUS); > + result = rx_fifo_status & RX_FIFO_WC_MSK; > + > + /* > + * Validate RX data with IRQ status > + * Only report pending data if valid RX IRQ indicators are set. > + */ > + if (result) { > + s_irq_status = readl(priv->base + SE_GENI_S_IRQ_STATUS); > + > + if (!(s_irq_status & (S_RX_FIFO_WATERMARK_EN | > S_RX_FIFO_LAST_EN))) { > + /* No valid RX IRQ, ignore stale data */ > + return 0; > + } > + } > + return result; > + } else { > return readl(priv->base + SE_GENI_TX_FIFO_STATUS) & > TX_FIFO_WC_MSK; > + } > > return 0;
It won't reach here... Reviewed-by: Varadarajan Narayanan <[email protected]> > } > > --- > base-commit: 6902fb4c17faa375003124c451c2550deab5463d > change-id: 20260629-uart-e07d893e4508 > > Best regards, > -- > Balaji Selvanathan <[email protected]> >
