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    SubjectRe: [PATCH v2 5/6] esp_scsi: De-duplicate PIO routines
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    On 10/15/18 8:25 AM, Finn Thain wrote:
    > On Mon, 15 Oct 2018, Hannes Reinecke wrote:
    >
    >> On 10/14/18 8:12 AM, Finn Thain wrote:
    >>> As a temporary measure, the code to implement PIO transfers was
    >>> duplicated in zorro_esp and mac_esp. Now that it has stabilized
    >>> move the common code into the core driver but don't build it unless
    >>> needed.
    >>>
    >>> This replaces the inline assembler with more portable writesb() calls.
    >>> Optimizing the m68k writesb() implementation is a separate patch.
    >>>
    >>> Tested-by: Stan Johnson <userm57@yahoo.com>
    >>> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
    >>> Tested-by: Michael Schmitz <schmitzmic@gmail.com>
    >>> ---
    >>> Changed since v1:
    >>> - Use shost_printk() instead of pr_err().
    >>> - Add new symbol CONFIG_SCSI_ESP_PIO to Kconfig.
    >>> ---
    >>> drivers/scsi/Kconfig | 6 +
    >>> drivers/scsi/esp_scsi.c | 128 +++++++++++++++++++++
    >>> drivers/scsi/esp_scsi.h | 5 +
    >>> drivers/scsi/mac_esp.c | 173 +----------------------------
    >>> drivers/scsi/zorro_esp.c | 232 ++++++---------------------------------
    >>> 5 files changed, 179 insertions(+), 365 deletions(-)
    >>>
    [ .. ]
    >>> diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
    >>> index d0c032803749..2590e5eda595 100644
    >>> --- a/drivers/scsi/esp_scsi.h
    >>> +++ b/drivers/scsi/esp_scsi.h
    >>> @@ -431,6 +431,7 @@ struct esp_driver_ops {
    >>> struct esp {
    >>> void __iomem *regs;
    >>> void __iomem *dma_regs;
    >>> + u8 __iomem *fifo_reg;
    >>> const struct esp_driver_ops *ops;
    >>> @@ -540,6 +541,7 @@ struct esp {
    >>> void *dma;
    >>> int dmarev;
    >>> + int send_cmd_error;
    >>> int send_cmd_residual;
    >>> };
    >>>
    >> These variables are only used within esp_send_pio_cmd(); consider making them
    >> conditional based on the config option.
    >>
    >
    > In the case of send_cmd_residual, that would mean a second #ifdef added to
    > esp_data_bytes_sent() where it gets used. I'm happy to comply but I fear
    > that all these #ifdefs may harm readability...
    >
    > There are already other variables in struct esp that may go unused, such
    > as dma_regs, that don't have #ifdefs to elide them. Are these also
    > problematic in some way?
    >
    The unused fields in the struct are not so much an issue; in fact, it
    rather complicated things when having individual fields in the struct
    surrounded by CONFIG_XXX, as then the order of the fields would change
    depending on the configuration. Which makes it really hard to debug ..

    However, the function declaration really is a worry, as the actual
    function body only exists when the config option is enabled.
    So either add a dummy function or surround the function declaration by
    CONFIG_ESP_PIO.
    Otherwise I think Dan Carpenter and the likes are guaranteed to send you
    a nice mail complaining about this ...

    Cheers,

    Hannes
    --
    Dr. Hannes Reinecke Teamlead Storage & Networking
    hare@suse.de +49 911 74053 688
    SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
    GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
    HRB 21284 (AG Nürnberg)

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