Re: [PATCH v4 2/4] mtd: nand: gpmi: add gpmi_move_bits function
From: Brian Norris
Date: Thu Nov 20 2014 - 04:22:28 EST
On Mon, Oct 20, 2014 at 10:46:15AM +0200, Boris Brezillon wrote:
> Add a new function to move bits (not bytes) from a memory region to
> another one.
> This function is similar to memmove except it acts at bit level.
> This function is needed to implement GPMI raw access functions, given the
> fact that ECC engine does not pad ECC bits to the next byte boundary.
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> drivers/mtd/nand/gpmi-nand/gpmi-lib.c | 129 +++++++++++++++++++++++++++++++++
> drivers/mtd/nand/gpmi-nand/gpmi-nand.h | 4 +
> 2 files changed, 133 insertions(+)
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> index 87e658c..5d4f140 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> @@ -1353,3 +1353,132 @@ int gpmi_read_page(struct gpmi_nand_data *this,
> set_dma_type(this, DMA_FOR_READ_ECC_PAGE);
> return start_dma_with_bch_irq(this, desc);
> +void gpmi_move_bits(u8 *dst, size_t dst_bit_off,
> + const u8 *src, size_t src_bit_off,
> + size_t nbits)
1) Yikes! This function is a little hairy.
2) This function really deserves a full comment header (kerneldoc?); it
needs to have clearly-documented high-level semantics.
I'm not sure how to address #1, as the complexity is necessary. Did you
run this through some unit tests, at least?
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