Claude review: Re: [PATCH] staging: fbtft: fb_ra8875: replace udelays with usleep_range

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Overall Series Review

Subject: Re: [PATCH] staging: fbtft: fb_ra8875: replace udelays with usleep_range
Author: Greg KH <gregkh@linuxfoundation.org>
Patches: 5
Reviewed: 2026-02-27T12:43:24.355510

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This mbox contains a v1 patch and its v2 respin, both by Jose A. Perez de Azpillaga, targeting `drivers/staging/fbtft/fb_ra8875.c`. The goal is to replace two `udelay(100)` calls in `write_reg8_bus8()` with a sleeping alternative to avoid busy-waiting in a non-atomic context.

**v1** used `usleep_range(100, 120)`. **v2** (the current revision) switches to `fsleep(100)`, which is the preferred modern API per reviewer feedback.

The change is **correct and appropriate**. The `write_reg8_bus8()` function is clearly in a sleepable context — it calls `write_spi()` → `spi_sync()`, which itself can sleep. The existing `init_display()` function in the same file already uses `mdelay()` for longer waits, further confirming non-atomic context.

For 100us, `fsleep(100)` will internally call `usleep_range(100, 125)` (based on the formula `usleep_range(usecs, usecs + (usecs >> max_slack_shift))` with `max_slack_shift=2`), which is a reasonable range and avoids the busy-wait of `udelay()`.

No functional concerns. This is a straightforward cleanup appropriate for staging.

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