| Message ID | 1499693302-25120-10-git-send-email-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 52078ca712cd933844721aaa700b3bd85234841f |
| Delegated to: | Simon Horman |
| Headers | show |
Hi Geert, On Mon, Jul 10, 2017 at 10:28 PM, Geert Uytterhoeven <geert+renesas@glider.be> wrote: > DMA for (H)SCIF(A|B) serial ports on Renesas R-Car Gen2 and RZ/G1 SoCs > is considered stable, hence enable it by default. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > --- > arch/arm/configs/multi_v7_defconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig > index ea2075d8e185f7aa..072a455008df9751 100644 > --- a/arch/arm/configs/multi_v7_defconfig > +++ b/arch/arm/configs/multi_v7_defconfig > @@ -330,6 +330,7 @@ CONFIG_SERIAL_IMX_CONSOLE=y > CONFIG_SERIAL_SH_SCI=y > CONFIG_SERIAL_SH_SCI_NR_UARTS=20 > CONFIG_SERIAL_SH_SCI_CONSOLE=y > +CONFIG_SERIAL_SH_SCI_DMA=y > CONFIG_SERIAL_MSM=y > CONFIG_SERIAL_MSM_CONSOLE=y > CONFIG_SERIAL_VT8500=y Thanks, FWIW I'm very happy to see DMA enabled for the SCIF driver in mainline. Since enabling DMA Engine still keeps PIO support around I wonder why we need this Kconfig at all - other drivers seem to get by without this kind of thing? So in my opinion it would also be nice to get rid of SERIAL_SH_SCI_DMA completely and reducing the number of special per-driver Kconfig entries. Cheers, / magnus
Hi Magnus, On Tue, Jul 11, 2017 at 5:38 AM, Magnus Damm <magnus.damm@gmail.com> wrote: > On Mon, Jul 10, 2017 at 10:28 PM, Geert Uytterhoeven > <geert+renesas@glider.be> wrote: >> DMA for (H)SCIF(A|B) serial ports on Renesas R-Car Gen2 and RZ/G1 SoCs >> is considered stable, hence enable it by default. >> >> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> >> --- >> arch/arm/configs/multi_v7_defconfig | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig >> index ea2075d8e185f7aa..072a455008df9751 100644 >> --- a/arch/arm/configs/multi_v7_defconfig >> +++ b/arch/arm/configs/multi_v7_defconfig >> @@ -330,6 +330,7 @@ CONFIG_SERIAL_IMX_CONSOLE=y >> CONFIG_SERIAL_SH_SCI=y >> CONFIG_SERIAL_SH_SCI_NR_UARTS=20 >> CONFIG_SERIAL_SH_SCI_CONSOLE=y >> +CONFIG_SERIAL_SH_SCI_DMA=y >> CONFIG_SERIAL_MSM=y >> CONFIG_SERIAL_MSM_CONSOLE=y >> CONFIG_SERIAL_VT8500=y > > Thanks, FWIW I'm very happy to see DMA enabled for the SCIF driver in mainline. > > Since enabling DMA Engine still keeps PIO support around I wonder why > we need this Kconfig at all - other drivers seem to get by without > this kind of thing? > So in my opinion it would also be nice to get rid of SERIAL_SH_SCI_DMA > completely and reducing the number of special per-driver Kconfig > entries. In general, I would agree, and remove the option at the blimp of an eye. However, this driver is shared with H8/300 and SuperH. While both could use DMA (but it's not supported by Linux yet), I don't know if they are willing to live with the increased static and dynamic memory footprint of SH_SCI DMA support. Whether we want to hide the option (and default to y if ARCH_RENESAS, i.e. ARM) is another question. Note that that wouldn't reduce code maintainability, as the #ifdefs would be kept, and it would prevent building and testing with/without DMA on ARM. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
On Tue, Jul 11, 2017 at 8:59 AM, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > Whether we want to hide the option (and default to y if ARCH_RENESAS, i.e. > ARM) is another question. Note that that wouldn't reduce code maintainability, > as the #ifdefs would be kept, and it would prevent building and testing > with/without DMA on ARM. arch/sh/configs/sdk7786_defconfig enables it, too, so it should at least be a user-selectable option on SuperH if you do that. Arnd
On Tue, Jul 11, 2017 at 8:59 AM, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > Hi Magnus, > > On Tue, Jul 11, 2017 at 5:38 AM, Magnus Damm <magnus.damm@gmail.com> wrote: >> On Mon, Jul 10, 2017 at 10:28 PM, Geert Uytterhoeven >> Since enabling DMA Engine still keeps PIO support around I wonder why >> we need this Kconfig at all - other drivers seem to get by without >> this kind of thing? >> So in my opinion it would also be nice to get rid of SERIAL_SH_SCI_DMA >> completely and reducing the number of special per-driver Kconfig >> entries. > > In general, I would agree, and remove the option at the blimp of an eye. > However, this driver is shared with H8/300 and SuperH. While both could use > DMA (but it's not supported by Linux yet), I don't know if they are willing to > live with the increased static and dynamic memory footprint of SH_SCI DMA > support. One more thing: enabling the DMA support in the console driver generally means you cannot use printk in the DMA driver anywhere that may be called during printk(). Not sure if that is a concern here. Arnd
Hi Arnd, On Tue, Jul 11, 2017 at 10:39 AM, Arnd Bergmann <arnd@arndb.de> wrote: > On Tue, Jul 11, 2017 at 8:59 AM, Geert Uytterhoeven > <geert@linux-m68k.org> wrote: > >> Whether we want to hide the option (and default to y if ARCH_RENESAS, i.e. >> ARM) is another question. Note that that wouldn't reduce code maintainability, >> as the #ifdefs would be kept, and it would prevent building and testing >> with/without DMA on ARM. > > arch/sh/configs/sdk7786_defconfig enables it, too, so it should at least be > a user-selectable option on SuperH if you do that. But that can't enable DMA, as (1) the non-DT DMA configuration was removed due to (2) being unused. Cfr. commit 219fb0c1436e4893 ("serial: sh-sci: Remove the platform data dma slave rx/tx channel IDs"). Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
Hi Arnd, On Tue, Jul 11, 2017 at 10:42 AM, Arnd Bergmann <arnd@arndb.de> wrote: > On Tue, Jul 11, 2017 at 8:59 AM, Geert Uytterhoeven > <geert@linux-m68k.org> wrote: >> On Tue, Jul 11, 2017 at 5:38 AM, Magnus Damm <magnus.damm@gmail.com> wrote: >>> On Mon, Jul 10, 2017 at 10:28 PM, Geert Uytterhoeven >>> Since enabling DMA Engine still keeps PIO support around I wonder why >>> we need this Kconfig at all - other drivers seem to get by without >>> this kind of thing? >>> So in my opinion it would also be nice to get rid of SERIAL_SH_SCI_DMA >>> completely and reducing the number of special per-driver Kconfig >>> entries. >> >> In general, I would agree, and remove the option at the blimp of an eye. >> However, this driver is shared with H8/300 and SuperH. While both could use >> DMA (but it's not supported by Linux yet), I don't know if they are willing to >> live with the increased static and dynamic memory footprint of SH_SCI DMA >> support. > > One more thing: enabling the DMA support in the console driver generally > means you cannot use printk in the DMA driver anywhere that may be called > during printk(). Not sure if that is a concern here. Not anymore, as all of these prints should have been removed/disabled already. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig index ea2075d8e185f7aa..072a455008df9751 100644 --- a/arch/arm/configs/multi_v7_defconfig +++ b/arch/arm/configs/multi_v7_defconfig @@ -330,6 +330,7 @@ CONFIG_SERIAL_IMX_CONSOLE=y CONFIG_SERIAL_SH_SCI=y CONFIG_SERIAL_SH_SCI_NR_UARTS=20 CONFIG_SERIAL_SH_SCI_CONSOLE=y +CONFIG_SERIAL_SH_SCI_DMA=y CONFIG_SERIAL_MSM=y CONFIG_SERIAL_MSM_CONSOLE=y CONFIG_SERIAL_VT8500=y
DMA for (H)SCIF(A|B) serial ports on Renesas R-Car Gen2 and RZ/G1 SoCs is considered stable, hence enable it by default. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- arch/arm/configs/multi_v7_defconfig | 1 + 1 file changed, 1 insertion(+)