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...@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...@samsung.com | (970) 672-0658 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
