Messages in this thread | | | Date | Sat, 22 Mar 2014 09:22:56 -0600 | From | Shuah Khan <> | Subject | Re: [PATCH] media: em28xx-video - change em28xx_scaler_set() to use em28xx_reg_len() |
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On 03/22/2014 06:32 AM, Frank Schäfer wrote: > > Am 21.03.2014 22:04, schrieb Shuah Khan: >> Change em28xx_scaler_set() to use em28xx_reg_len() to get register >> lengths for EM28XX_R30_HSCALELOW and EM28XX_R32_VSCALELOW registers, >> instead of hard-coding the length. Moved em28xx_reg_len() definition >> for it to be visible to em28xx_scaler_set(). >> >> Signed-off-by: Shuah Khan <shuah.kh@samsung.com> >> --- >> drivers/media/usb/em28xx/em28xx-video.c | 29 ++++++++++++++++------------- >> 1 file changed, 16 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c >> index 19af6b3..f8a91de 100644 >> --- a/drivers/media/usb/em28xx/em28xx-video.c >> +++ b/drivers/media/usb/em28xx/em28xx-video.c >> @@ -272,6 +272,18 @@ static void em28xx_capture_area_set(struct em28xx *dev, u8 hstart, u8 vstart, >> } >> } >> >> +static int em28xx_reg_len(int reg) >> +{ >> + switch (reg) { >> + case EM28XX_R40_AC97LSB: >> + case EM28XX_R30_HSCALELOW: >> + case EM28XX_R32_VSCALELOW: >> + return 2; >> + default: >> + return 1; >> + } >> +} >> + >> static int em28xx_scaler_set(struct em28xx *dev, u16 h, u16 v) >> { >> u8 mode; >> @@ -284,11 +296,13 @@ static int em28xx_scaler_set(struct em28xx *dev, u16 h, u16 v) >> >> buf[0] = h; >> buf[1] = h >> 8; >> - em28xx_write_regs(dev, EM28XX_R30_HSCALELOW, (char *)buf, 2); >> + em28xx_write_regs(dev, EM28XX_R30_HSCALELOW, (char *)buf, >> + em28xx_reg_len(EM28XX_R30_HSCALELOW)); >> >> buf[0] = v; >> buf[1] = v >> 8; >> - em28xx_write_regs(dev, EM28XX_R32_VSCALELOW, (char *)buf, 2); >> + em28xx_write_regs(dev, EM28XX_R32_VSCALELOW, (char *)buf, >> + em28xx_reg_len(EM28XX_R32_VSCALELOW)); > Hmm... registers 0x30 and 0x32 are always 2 bytes long. > So this change would needlessly complicate the code. >
The reason I made the change is that em28xx_reg_len() is handling these two registers and I thought it would be good to make it consistent with other writes to these registers and not hard-code the length.
I think it would help with maintenance later by avoiding hard-coding the length and use the existing routine that returns the length for these registers.
You are correct that it does add a function call in the code path. So if you think the trade-off isn't worth it, I am not going to argue with it :)
-- Shuah
-- Shuah Khan Senior Linux Kernel Developer - Open Source Group Samsung Research America(Silicon Valley) shuah.kh@samsung.com | (970) 672-0658 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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