Hi Greg,
On Thu, 2 Oct 2025 17:43:52 +0200
Greg KH <gregkh@linuxfoundation.org> wrote:
> On Thu, Oct 02, 2025 at 10:57:24AM -0400, Hugo Villeneuve wrote:
> > From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> >
> > Commit 43c51bb573aa ("sc16is7xx: make sure device is in suspend once
> > probed") permanently enabled access to the enhanced features in
> > sc16is7xx_probe(), and it is never disabled after that.
> >
> > Therefore, remove useless re-enable of enhanced features in
> > sc16is7xx_set_baud().
> >
> > Fixes: 43c51bb573aa ("sc16is7xx: make sure device is in suspend once probed")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> > ---
> > drivers/tty/serial/sc16is7xx.c | 7 -------
> > 1 file changed, 7 deletions(-)
> >
> > diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> > index 1a2c4c14f6aac..c7435595dce13 100644
> > --- a/drivers/tty/serial/sc16is7xx.c
> > +++ b/drivers/tty/serial/sc16is7xx.c
> > @@ -588,13 +588,6 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud)
> > div /= prescaler;
> > }
> >
> > - /* Enable enhanced features */
> > - sc16is7xx_efr_lock(port);
> > - sc16is7xx_port_update(port, SC16IS7XX_EFR_REG,
> > - SC16IS7XX_EFR_ENABLE_BIT,
> > - SC16IS7XX_EFR_ENABLE_BIT);
> > - sc16is7xx_efr_unlock(port);
> > -
> > /* If bit MCR_CLKSEL is set, the divide by 4 prescaler is activated. */
> > sc16is7xx_port_update(port, SC16IS7XX_MCR_REG,
> > SC16IS7XX_MCR_CLKSEL_BIT,
> > --
> > 2.39.5
> >
> >
>
> Why is this needed for stable kernels? It's useless, what is it
> harming?
It is useless, and doing no "harm", but since the device is on a SPI
or I2C bus, this is inefficient as it takes precious cycles on these
busses.
> If so, please send it separately, not as a part of a larger series.
That is why this patch is the first in the series, so that it could be
easily backported. But I can send it separately, sure.
Hugo.